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Your input is important to us. Please provide your valuable feedback. Here are some testimonials from our clients:

Hi Mark S,

Thanks for the email. The ECU upgrade is absolutely phenomenal. The car runs the same as stock in the sense that it runs SMOOTH! The only big difference is the crazy amount of power it now produces. I took it to Moroso speedway Friday night and everyone was in awe with the way it performed and sounded. I was running high 11’s all night. The transmission is TOTALLY different. It shifts faster than it ever did, no more lag in between gears just bang, bang, bang.

Mark W.

2010 (W204) C63
Posted By: RENNtech
I just wanted to thank you again Mark S. for all your help with the ECU and spark plug upgrade. Your knowledge and help we're top notch and really made me feel comfortable.

With every concern you were only a phone call away to answer my question, regardless of how stupid. And as far as the performance in my e63 after the upgrade? All I can say is WOW. It really woke up the beast. It's like a different car but in a good way. I will be calling you soon to order more parts.
Thank you again.


Wolfgang S.

2012 E 63
Posted By: RENNtech

The difference was like night and day. I will display the decals proudly.


Greg H.

2007 Mercedes Sprinter Van
Posted By: RENNtech
I just had my second MINI Tuned by Renntech with the help of Mark Squadrito.

The car feels so alive now, you almost have to relearn how to drive it! Mark has given me suggestions on different parts to use and always is there to answer my questions.

I work for a MINI Dealership and currently trying to get Renntech's products and service offered to our clients . Thank you for all of your service.

Alan R.
2012 Mini Cooper S
Posted By: RENNtech
Mr. Mark Squadrito,

I want to thank you and cannot begin to tell you how amazed and pleased I am with the Renntech ECU tune. Absolutely noticeable gains all across the board, the increase in boost is not only felt, but turbos really work and hiss and are available the second you hit above idle. There is also a pleasing roar of the motor at higher rpms. The down shifts are now so much more fluid and properly matched, didn't expect that. It's all just so perfect.

And the ease of the entire process of removal and installation, with your consultation and guidance has me completely impressed and 100% satisfied. Just as you promised, over-nighted the ECU to you, re-tuned, sent back next day; 128hp & 163 tq gain in less than 48 hours. Amazing job and service. Cannot wait for next upgrade.
Now, I just gotta figure out a way to keep it on the road.
Its just simply 'superb'.

Renntech has made me such the dedicated follower that I will only be purchasing Mercedes and upgrading with Renntech tunes.

Love it! Bravo!

Thank you again Mark, and to the entire Renntech team!

Albert P.

2012 (C207) E550c (M278)
Posted By: RENNtech
Hello Dian,

I received the ECU and installed it immediately. I didn't want to send you a note until after having a full opportunity to experience my new found power during the long holiday weekend. The car exceeds all expectations and I am very thankful for choosing RENNtech. The power delivery in all modes is precise and addicting.

Again, I cannot thank you enough, as the choice was made easier by your professionalism and very informative responses to my many questions. I searched/inquired around w/ all the other tuners, but in the end you made my choice easier.
Thank you!

Best regards,

Roy S.

E 63 Biturbo (W212)
Posted By: RENNtech
Hi George,

The tune is amazing. The acceleration after the tune was completely unexpected. I saw the numbers but it’s hard to believe that it was the same car. The shift acceleration from gear to gear is just as impressive.

Thanks again


2012 E 550 (W212)
Posted By: RENNtech
Hi George,

I put my ECU in yesterday and had MB put in my new plugs and air filters today. The car is absolutely incredible; feels like a completely different car. The daily drivability is as good if not better than stock.

Through my own research and my conversations with you I felt very comfortable letting Renntech upgrade my vehicle. During this process we had spoken on several occasions and I want to personally thank you for your time, guidance and professionalism. You made my decision to choose Renntech very easy.

P.S. My wife's first experience with the new found power brought her stomach to her throat and grabbing whatever she could find to hold on to, all while screaming at me to slow down! That was definitely worth the price of admission!

I would highly recommend Renntech and George to anyone considering upgrading their Mercedes.

Thanks again!


2013 CLS63 PP (C218)
Posted By: RENNtech
Hi George, I got the ECU, Plugs and Filters installed and the car is nothing short of amazing. Please give my appreciation to the Renntech team for delivering another great product.

The drive-ability and performance are awesome. This car scares me more than my previous Renntech SL65 - It just wants to go FAST and it does!

More to come ...needs lowering and Aero effects


2012 CLS 63 Biturbo (C218)
Posted By: RENNtech
Dear Jesse,

Thank you for getting the ECUs back to me on time.
With the new ECUs the transformation of the car is like magic! Improved drivability, better throttle response, and amazing power. This is how the car should have been built by Bentley!
Can you believe that at 2000 RPM I am doing over 70 MPH? Again, truly amazing and thank you.

Best wishes,


2011 Bentley Flying Spur
Posted By: RENNtech

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