March 16, 2024

RENNtech returns to GT4 America for 2024 Season

 Michael Auriemma Returns to RENNtech
Partners with IndyCar’s Matheus Leist
for Championship Chase! 

STUART, FL - After his debut season with RENNtech Motorsports in 2023, Michael Auriemma returns to race the #89 RENNtech AMG GT4 in SRO’s GT4 America.

The RENNtech #89 will move up to the Pro-AM class with Michael’s new codriver, Matheus Leist, for the 7-round, 13-race season. Making his GT debut at the age of 25, Leist comes with an impressive racing resume. Matheus previously raced two seasons in IndyCar as well as Daytona Prototypes in the IMSA Sportscar- Challenge. His invaluable experience at the highest levels of American racing elevates the team to championship contention. 

Michael Auriemma, Driver #89:
“Last year was a great experience after a ten-year hiatus. Now I feel like I’ve got the rust off and I’m ready to take a step forward. I’m excited to be back in the RENNtech car with a crew that feels like family and to be moving up to Pro-AM with a super talented co-driver.” 

Matheus Leist, Driver #89: 
“Last year I had the pleasure to work with Michael and RENNtech as a driver coach, and this year I’ll be stepping into the driver’s seat once again. I’m very excited to work with such a great group of people. I’m looking forward to 
the challenge and I can’t wait for the first race of the season.” 

Also under the RENNtech tent for 2024 is the previously announced addition of the OnlyFans #43 P1 Groupe AMG GT4. After one season in GT America, Alex Vogel joins the team to pair up with Matt Bell in the Pro-AM class of GT4 America. 

After two successful test at Sebring International Raceway during the Off-Season, RENNtech will start its two-car 2024 season effort with pre-season testing 
in Sonoma before the season opener in April. 

Hartmut Feyhl, Owner: 
“After only one podium in 2023, we as a team are fully committed and ready to make the needed investments to bring race wins and championship aspirations back. Having Michael back and pairing him up with a talent like Matheus is a big step in the right direction.” 

The 2024 season opener is once again at Sonoma Raceway in California on April 6. RENNtech’s hometown race has been moved to early May, before traveling to Austin, Texas. The round-three race at COTA is the endurance debut for GT4 America. Instead of the usual two one-hour races per weekend, a single three-hour race will determine the winner.
After the summer break, racing will start back up at VIRginia International Raceway and Wisconsin’s Road America. The September slot previously filled by Sebring has been taken over by Barber Motorsports Park. 2024 will mark the first time since 2016 that SRO-America races in Birmingham, Alabama.
The season finale will be held once again in Indianapolis in early October. 

2024 GT4 America Schedule: 

April 5-7
Sonoma Raceway 

May 3-5
Sebring International Raceway 

May 17-19
Circuit of The Americas 

July 19-21
VIRginia International Raceway 

August 16-18
Road America 

September 6-8
Barber Motorsports Park 

October 4-6
Indianapolis Motor Speedway

February 27, 2024

RENNtech Builds World Record AMG GT63 S Edition 1

Is there a better way to celebrate the 35th Anniversary year than setting a new record?
Not if you are RENNtech.

The AMG GT63S Edition 1 is back - and faster than ever.

Early February 2024, the owner of Graphite Magno Edition 1 AMG GT63S that we first wrote about in June of 2023, sent us pictures of his new yellow graphics and custom magnesium wheels along with a enthusiastic note.

👍WOW, this car you did for me is different than anything I’ve ever owned. I just took her out for a run and it did a 4.92 second 60-130 time. That’s more than a second faster than last May.

The email came from long-time owner who prides himself on buying high end Mercedes vehicles, customizing their look and maximizing their performance. He chose RENNtech with the goal to own the fastest AMG GT63S on the planet, and the attached screen captures proved it. Mission accomplished.

The attached image contained Dragy results showing a ¼ mile time of 9.79 seconds. This was .20 tenths quicker than the run recorded last May crushing the prior ¼ mile record of 9.99 seconds. The new time is the fastest time published and recorded for the Mercedes-AMG GT63S 4-door (X290).  To top it off, looking at the Dragy we noticed a "lift" towards the end. Why? “I just didn’t want to push it too hard.

Dragy results show a 9.79 second 133.11 mph quarter mile time - even with a lift of throttle at the end.
The 4.92 second 60 - 130 mph is equal to the fastest supercars in the world.

While the 9.79 time is a record shattering and the fastest ¼ mile on record, the 4.92 second time from 60 mph to 130 mph matches the speed of supercars.  Compare what we have to work with…so we did. Lining it up to a rolling 60 – 130 mph vs. a Ferrari SF90 (4.97 seconds), or the LaFerrari (5 seconds) and they will find how fast it really is. Very Fast.

The results would have been even better from a rolling start, but due to the owner driving the car sparingly, we will have to wait for additional results from his next outing.

So how did we get here? With over four decades dedicated to developing the fastest MB's on the planet, RENNtech leads the field in engineering and development of the highest grade in performance upgrades for Mercedes-Benz AMG and European performance vehicles. The considerable investment of time and resources dedicated to engineering and design delivers rock solid reliability beyond other tuners, at a level that owners of AMG vehicles expect from the factory.

“This car deserves to get the credit for its record setting results, but RENNtech deserves the accolades for the 100's of hours of customized tuning & engineering to get it there. This summer the car was producing over 1000 HP at the wheels even with all the heat and humidity of South Florida. I did not remove any seats, no roll cages, and don’t use E85, methane, nitrous bottles, drag slicks, or any other tricks of the trade to improve times, so I knew it could go even faster when the weather cooled off." 
Said Owner (@ed1t1ongt63s)

AMG GT 63 Edition 1 - DYNO Pull

The all-out AMG GT63 S Edition 1 (X290), that is a one-of-a-kind 1000 WHP family rocket ship with the daily comfort and reliability of a M.B. AMG. During the initial development stage in June, this beast set the record of highest power output measured on RENNtech’s dynometer (video), the first sub 10 second ¼ -mile time, and most powerful AMG GT63 S at that time.

How much faster?

“Good question. I really don’t know.. I have no intention on pushing the limits. Maybe that is question for the next owner, but my hat is off to RENNtech for building this amazing machine for me”.
Said Owner


The underpinnings of the AMG GT63 include RENNtech Stage II Turbo’s, ECU tuning, Carbon Fiber Air Intakes, Intercooler, Downpipes with 200 Cell Catalytic Converters, Stainless Steel Mufflers, High Pressure Fuel system, Transmission (TCU) and Drivetrain (CPC) upgrades. In addition, the custom DYNO tuning in order to optimize the car for ¼ mile runs and launches were done by RENNtech – making this rare AMG GT63S Edition 1 the fastest in the world.

November 27, 2023

Best sounding upgrade for BiTurbo V8 Mercedes-AMG

RENNtech Stainless Steel Downpipes for M177 V8 BiTurbo Engines.

The amount of sound a vehicle makes is mostly dependent on the flow of the exhaust system, which can be broken into three main parts; Headers/Downpipes, Mid-Pipe, and Mufflers/Resonators.

Downpipes are the "hot-end" in turbo-charged exhaust systems. They connect the exhaust manifold to the pipes that lead exhaust gasses down through the catalytic converters toward the mufflers and out exhaust tips.

The Headers / Downpipes are the first point in the flow and sound of exhaust. The factory Mercedes-Benz AMG catalytic converters are designed capture harmful particles and to meet global emissions regulations. For most part the AMG exhaust systems have good flowing cats as they know less restrictive means better MPG and reduced emissions.  

RENNtech stainless steel downpipes are equipped with 200 Cell Catalytic Converters, which capture the same particles as stock set. RENNtech downpipes are designed for motorsport applications, maximizing the power and performance of the engine. The robust exhaust note and no Check Engine Light is the cherry on top, making the system a favorite of AMG owners. 

Downpipes and headers are custom built by our in house fabrication department at RENNtech's headquarters in Stuart, FL. Available for most Mercedes-Benz AMG models, the downpipes are the best solution for those looking for a little bit more from their car. 

June 26, 2023

The One that Set the Record.

In this edition of RENNtech Performance Blog, we will dive into the performance development and extraordinary achievements of the RT engineering team and the car that broke the RENNtech Dyno record.

In late January we received a call from a customer who acquired a low mile AMG GT63S Edition One. The customer wanted to know about our GT63 (S) and M177 Engine development, and if it was possible to turn his Edition One into a 9 Second ¼ mile car. This had to be achieved without removing any seats or adding nitrous, and the car needed to run on factory Michelin Pilot Sport 4S street tires, and 93 Octane fuel for daily comfort.

Once the project was outlined and approved, development began at RENNtech headquarters in Stuart, Florida. During several weeks of development and testing in various stages, the results showed promise. The increased flow of air proved to be crucial for the M177 to deliver an astounding 1196 crank HP, 1006.96 WHP, and 935lb of TQ running on 100 Oct Gas.

This is the most powerful RENNtech AMG GT63S in the world, and set a new RENNtech power record by being the first vehicle to break the 1000 WHP mark measured on RENNtech’s Dyno. The Dyno has seen some of the fiercest Mercedes-AMG developments over the past decade, but none had spun the 4-wheel Dyno with this much power.

During road testing, under challenging conditions of a hot Florida day with high humidity and density altitude, the Edition One broke the 10 Second ¼ mile barrier, clocking a quarter-mile time of 9.99 seconds on street tires and no prep. This record setting performance makes it one of the fastest 4-door vehicles ever, and the fastest AMG GT63S Edition One (X290) built by RENNtech.

These cars are quite amazing. The amount of power we have been able to unlock from the M177 engine is incredible, and this development proved how strong the engine can be. With the increased airflow from our carbon fiber airboxes and the right tuning, we were able to gain massive power without compromising usability. Combined with the X290 -chassis, what we have developed is a 1000 WHP Mercedes-AMG that is incredibly fast and perfectly suited for daily driving”.  Said Hartmut Feyhl, President, RENNtech.

With its unrivaled capabilities the Edition One is a testament to the expertise and craftsmanship of RENNtech, as well to the passion of the owner who chose to pursue performance without compromise and chose RENNtech for the development.

My objective was to make a unique one- of-a-kind super car that no one else in the world has, and RENNtech was able to deliver. It’s a special car that I can occasionally take out for a night on the town, to a car show, or an occasional spirited drive.” said the Owner  @ed1t1ongt63s 

What sets RENNtech apart from other tuners is their commitment to transparency & verifiability. They publish information that can be substantiated with Dyno charts and videos, ensuring that every claim is backed by tangible evidence. They also go beyond raw power, prioritizing the performance, safety and reliability of their tuned vehicles on the road”. the Owner continued.

While many aspire to redefine automotive boundaries, this rare RENNtech built AMG GT63 Edition One managed to surpass all expectations, with unrivaled performance steeped in Mercedes-Benz AMG luxury and reliability. With its awe-inspiring performance, this unique AMG GT63 S Edition One stands above the rest and has etched its name to a long list of legendary RENNtechbuilds.

*Due to the high degree of development and tuning, power levels that exceed 1000 WHP are only available through RENNtech headquarters in Stuart, FL. 

June 7, 2023

RENNtech Unveils the 1196 HP Limited Edition Mercedes-AMG GT63 4-Door Coupe RIIIx .


RIIIx : The Most Powerful RENNtech Upgrade Ever1196 HP | 871 LB-FT

We are proud to announce the launch of our latest creation based on the Mercedes-AMG GT 63 RIIIx. With superior power and advanced performance tuning, the limited edition RIIIx is set to claim its place at the top among street-legal 4-door vehicles in the world.

The RIIIx is powered by the Mercedes-AMG twin-scroll M177 BiTurbo V8, producing equipped with RENNtech’s Stage II high-performance turbochargers that feature larger inducer and exducer wheels along with a special core assembly featuring reinforced axial bearings for less rolling resistance and zero lag.

To ensure the engine receives the necessary air flow and fuel supply, the GT63 RIIIx is fitted with an integrated carbon fiber air intake system with a 30% larger filter surface, and high-pressure fuel pumps. The exhaust system features RENNtech stainless-steel high-performance downpipes with free-flow 200 cell catalytic converters and upgraded performance mufflers produced specifically for the AMG GT63.

Thanks to RENNtech’s Transmission Control Unit (TCU) and Powertrain (CPC) upgrades, the RIIIx boasts lightning-fast acceleration, achieving 0-60 mph in 2.44 seconds and 0-100 mph in 5.5 seconds and a quarter-mile time under 10 seconds, the RIIIx was built to blow the all the doors off the competition.

Through an extensive series of tests on the Dynamometer, RENNtech Engineering revised ECU mapping for injection, ignition, and boost pressure control  as well as real-world test drives on the road and at the track. 

The peak output of 1196 HP and 927 LB-FT of torque is produced at 6,200 rpm on 100 octane fuel, and 964 HP and 846 LB-FT of torque on 93 octane fuel. The driver can easily switch between octane ratings using the Hand-Held Tuner, offering the option for maximum power and convenience for daily driving.

The RIIIx’s exterior carbon fiber aero package includes functional styling elements to produce more downforce for improved handling and stability at high speeds and the aesthetics of the GT63. These highly refined aero components were designed by RENNtech and are constructed in the USA using aerospace-grade pre-preg carbon fiber. 

With the record braking power figures, RENNtech Engineering has once again demonstrated its commitment to innovation, performance, and design. For a lucky few, the RIIIx is an exceptional vehicle that combines Mercedes-AMG cutting-edge technology and engineering with unparalleled power, making it one of the fastest four-door vehicles on the market.


  • 1196 HP & 927 LB-FT (100 Oct.)
  • 965 HP & 817 LB-FT (93 Oct.)
  • Carbon Fiber Air Boxes
  • Stage II Turbo Upgrade
  • Downpipes with 200 Cell Catalytic Converters
  • Stainless Steel Performance Mufflers
  • ECU Programming
  • Transmission Control Unit programming
  • Powertrain Control Unit programming
  • High Pressure Fuel system
  • Blow Off Valves
  • Hand Held Suspension Module
  • Exhaust Valve Module
  • Heat Exchanger


  • Carbon Fiber Front Splitter and Canards
  • Carbon Fiber Side Skirts
  • Carbon Fiber Rear Diffuser
  • Carbon Fiber Adjustable Rear Wing with Fixed Base
  • RENNtech RIIIX badging


  • RENNtech RPS 10.2 Forged Aluminum Monoblock wheels
  • Front: 21 x 10.0”
  • Rear: 22 x 12.0”
  • Michelin Pilot Sport 4 S
  • Front: 275/35 ZR 21
  • Rear: 335/25 ZR 22

Carbon Fiber Side Skirts and Forged RPS 10.2 Wheels

Carbon Fiber Rear Wing with Fixed Base

Carbon Fiber Front Splitter with Canards

Carbon Fiber Rear Diffuser

May 15, 2023

RENNtech Motorsports scores first Podium of the Season

Watch the highlights of Race 1 at NOLA Motorsports Park.

A flawless performance in New Orleans, puts Michael Auriemma and Tommy Johnson and the MB Gram #89 RENNtech AMG GT4 on the podium in the AM Class.

After qualifying in an outstanding P6 in Class, Tommy Johnson started the Sunday race for RENNtech. Johnson pushed hard while avoiding a couple early race scuffles as he was able to survive both Safety Car periods without any incidents.

Tommy Johnson started Race 1 P6 and gained one position before driver change.

At the half way mark, Michael Auriemma took over from Johnson with the car in P5. While steadily increasing his pace, Michael closed the gap to the leading cars. He crossed the checkered flag close to our competitors and steered clear of a few potential incidents. The #89 AMG GT4 finished P3 in class due to 2 post race penalties and scored the first podium for RENNtech Motorsports in 2023.
Michael Auriemma started race.

Michael Auriemma continued the race in P5 and finished P, getting our first podium of the season.

“We had a good weekend - the Team delivered a great car for the race and scoring our first podium feels fantastic! We intend to capitalize on this momentum moving forward, and we’ll be looking for more Podiums at COTA” said Team Owner Hartmut Feyhl.
Severe weather on Saturday led to delays in the schedule. Due to the nearing sunset, Saturdays Race ultimately had to be postponed and will be made up during Round 6 at Sebring International Raceway Sep 22-24. With only Race 1 in the books, RENNtech Motorsports left NOLA with 15 additional points keeping MB Gram #89 RENNtech Motorsports AMG GT4 in the hunt for the championship.

The next race weekend will be held May 19 – 21, at the Circuit of the Americas in Austin, TX.
For more about the RENNtech Motorsports program, please visit our website and follow us on Instagram and Facebook.

May 9, 2023

RENNtech Open Garage

On the 22nd of April, we hosted our second Open Garage event. We extended an invitation to our  friends, family, and esteemed customers to participate in a unique and engaging experience. The event provided an opportunity to dive into the technical aspects of our projects, while indulging in delicious snacks and refreshing drinks provided by Celsius and Muscle Vodka and the life size Eurosim F1 simulator.

Public events are a part of car culture, and RENNtech company has participated in dozens of shows, events, and happenings over the past year. As we opened our doors to allow visitors to witness our operations up close, our engineers, techs, and product specialists were available to chat and offer insights into the day-to-day workings of our business. Attendees were able to witness our tuning processes with a Ferrari F488 Spider on the dyno, followed by a TechTalk presentation on the performance development of the AMG GT and GT63 models.

The event was a great success, and we received positive feedback from attendees. We would like to thank everyone who attended, and we look forward to welcoming you to our next Open Garage event.

April 11, 2023


Pirelli GT4 America
SONOMA 2023 Wrap Up

SRO’s Pirelli GT4 America -series is one of the most exciting and intense GT -racing series in the world. The 2023 season opener at Sonoma Raceway was no exception, with some of the best GT -teams and drivers from around the world competing for the top spot. The RENNtech Motorsports team along with drivers Michael Auriemma and Thomas Johnson, was fully geared up to deliver a dominant performance with the MB Gram RENNtech Motorsports #89 AMG GT4.

The weekend started off with practice sessions, where both drivers had a chance to show their potential and posting an impressive lap time of 1:49:781 in the second session. The team's engineers worked hard to fine-tune the car for the qualifying rounds where Tommy Johnson posted a 1:48:258 lap time good enough for P26 overall in a grid of 43 cars.

Race 1 was a thrilling display of door-to-door racing in one of the most scenic raceways in America. After a bumpy start, the 60-minute-long race ran its course without major incidents, with Michael Auriemma bringing the car across the finish line P15 in class.

Race 2 brought the same intensity to the track. Starting from P36 overall Michael Auriemma drove a clean first stint, handing over the reins to Tommy Johnson midway of the race. After a crash brought on a full course yellow at the final minutes of the race, Tommy Johnson secured a P6 in class.

The team and drivers showed their ability to compete at the highest level, with the MB Gram RENNtech Motorsports #89 AMG GT4 proving to be very quick on the grid. The team's engineers and mechanics also demonstrated their skills, keeping the car running smoothly throughout the weekend.

In conclusion, the opening of the Pirelli GT4 America series at the Sonoma Raceway was a thrilling event, showcasing the growing popularity of GT -racing in America. The RENNtech team put up a strong performance in this very demanding race. Each race is a great experience which helps us get even stronger. We can't wait for the next heat at NOLA Motorsports Park, April 29 – 31.
Let’s race!

April 4, 2023

Project G - RENNtech Classic Performance

Classic restoration is becoming a significant part of RENNtech’s craft. The iconic G Wagen, in particular, holds a special place in the heritage of Mercedes-Benz. What you see is 1993 Mercedes-Benz G Class X461; a military vehicle that served for the Swiss Army.

In 2018, a client of ours imported this vehicle from the Netherlands, where it had undergone partial restoration and repaint in classic M.B. China Blue (934). Furthermore, the car had been fitted with a range of new components, including suspension, top, and a set of wheels, to bolster its aesthetic appeal.

Built for military purpose and off road travel, the Gelande Wagen (German terminology for G Wagen), was in a good shape but was severely underpowered for modern daily driving. Dyno tested at RENNtech, the 2.3-liter 4-cylinder M102 produced 70 WHP which good for traversing backroads of the Austrian alps, but not enough accelerate and keep up with South Florida highway traffic, so the owner turned to us create something more powerful for enjoyable and safe daily driving.

Being familiar with improving the performance and driving characteristics of G Class, we chose the rock-solid M.B. 5.5 liter M113 V8 -engine with 350 HP, and matching it to a 722.6 G 5 speed automatic for modern day performance.

The military purpose truck base is much different from road going vehicles, and the “little blue truck” will need several updates and modifications to fit the new powerplant and drivetrain, before the focus can shift to the development of a bespoke interior tailored to this vehicle.

Stay tuned!

Removing the original 2.3-liter 4-cylinder M102
Mercedes-AMG M113 5.5 -liter V8
G-Wagen ready to receive more power.
New motor mounts are part of fitting the V8 in place of the 4 -cylinder.

February 15, 2023

RENNtech Power Module for Range Rover

Known for Mercedes-Benz AMG performance tuning, RENNtech’s Power Module (RPM) now offers the same powerful ECU tuning for a wide range of European Luxury and Performance vehicles.

The most recent addition to the list of RENNtech tuned vehicles is the 2023 Land Rover Range Rover. Powered by a 4.4 liter Twin Turbo V8 the factory published power figures are 523 HP and 553 LB FT of torque. Tested on the DYNO at RENNtech, the Range Rover produced 588 HP and 650 LT-FT of torque, 65 HP and 97 LB-FT more power than advertised.

The RPM is a “piggy-back” style ECU upgrade designed to pull additional power from the engine by adjusting fuel-to-air ratio, ignition timing, and throttle mapping through RENNtech’s proprietary software.

With RENNtech’s software, the Range Rover engine produces an additional +57 HP and 40 LB FT of torque at the crank, delivering a totalof 654 HP and 690 LB-FT of torque!

With tune installed, the Range Rover feels equally smooth as before, but is quicker from the start with a stronger pull at higher speeds. Most noticeable are the pulls between 60 and 130 mph where the 5500+ lbs Range Rover needs it the most.

The RPM is designed for daily driving and comes with RENNtech’s standard 2 year product warranty. Installing the RPM is straightforward and can be done within 2-3 hours by one of RENNtech’s Dealers, or, if mechanically inclined with proper tools the install can be done at home.

The Range Rover sits at the top of the luxury SUV food chain, and with RENNtech’s Power upgrade the Rover inches closer to AMG GLS 63 in performance.


January 24, 2023

2023 Supercar Week

Supercar Week 2023 West Palm Beach.

SuperCar Week 2023 was nine days of automotive events hosted throughout Palm Beach County. This year the weeklong series of events culminated at the Grand Finale on the West Palm Beach Waterfront, with over 100,000 enthusiasts gathering to participate in the excitement.

RENNtech AMG GT Development Vehicle. 

RENNtech showed up in force, staking a claim on the lawn for modern and classics Mercedes-Benz and a selection of pre-merger AMG’s. Visitors got up close and personal with RENNtech Development Vehicles, the AMG GT and CLS 53 AMG, while our Engineer’s were on hand answering questions and talking cars.

RENNtech Development Car, CLS 53 AMG.

The gullwing doors of the SLR McLaren, one in silver and another 722 -version in black, were showstoppers and are destined to draw a crowd anywhere these very special vehicles show up. The SLR “super grand tourers” still look striking among the super and hyper cars of today. 

Mercedes-Benz SLR McLaren 722 edition.

RENNtech Classics received a great amount of attention and as a result started fascinating conversations between Hartmut Feyhl and visitors. With the growing interest in pre-merger AMG vehicles, RENNtech has become the destination for collectors who are looking to bring back the performance of these iconic machines.

The Originals. Hartmut Feyhl and 1985 Mercedes-Benz 300 E 6.0 AMG "Hammer" 

This year we were lucky to bring the original E300 6.0 AMG “Silver Hammer” which was restored and repowered at RENNtech in 2022. The Hammer was flanked by a 560 SEL 6.0 AMG, and a fully restored 560 SEC 6.0 Widebody.

RENNtech Classics restored 560 SEC 6.0 Widebody

These special vehicles got to share a ride with RENNtech Motorsports #89 MB Gram AMG GT4 in the Motorsports Team trailer. Part of the Race Village, the AMG GT4 was resting on the lawn in front of mega yachts enjoying the cool and sunny day before heading to pre-season testing for the upcoming SRO GT4 America -season.

RENNtech Motorsports #89 MB Gram AMG GT4 Racecar

Big shoutout to the everyone at RENNtech that worked hard and brought their best to the show, and all the men and women who brought a great variety of extraordinary cars to make this show a success. None of this would have been possible without the exceptional work of Neil London, SuperCar Week President and Executive Producer. 

It was a pleasure to exchange views and thoughts with other car enthusiasts, and we are already looking forward to next year!