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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,
Just wanted to drop you a line to say thank you for the excellent customer service and the tour of the facility, very interesting.
The Upgrade performed on my S600 has improved performance immensely, this is my second upgrade from Renntech and I will be back very soon.

Many thanks
Nick Inglis.
Posted By: RENNtech
I just wanted to express my sincere appreciation to one of your staff…Dian Esterhuyse. I have a testimonial on your site from May 29, 2013. However, I have recently had additional questions pertaining to upgrading my E63 (i.e.. Sport mufflers and spark plugs) and upon searching the various forums online…there was a lot of information to wade through. So inevitably, I contacted Dian directly and once AGAIN, he took the time to explain my options and helped to alleviate any concerns that I may have and more importantly helped me to weed out the bad information online. I have purchased the sport mufflers and will be having them installed shortly.

Again, I wanted to express my sincere appreciation to Dian and the time he has taken to help me w/ all my E63 questions…A VERY HAPPY RENNTECH CUSTOMER!

Roy Swartz
Posted By: RENNtech
Mercedes-Benz of Rocklin California S63

This S63 is the fastest Benz, possibly the fastest car, that I have ever been in!! holy crap is it awesome!

-Brandon Stevens
Posted By: RENNtech
To Whom It May Concern:

I recently purchased a 2011 Mercedes Benz S550 4Matic, 5.5 Litre V8. It drove OK but lacked throttle response and the quickness of my C Class. I called RENNtech and spoke to John Bologna (GREAT GUY) about updating my ECM. I realize I wouldn't get the HP increase of a bi turbo but was hoping I would get better throttle response. John assured me it would do everything I wanted. So with trepidation and $1590.00 I removed (yes me not a shop) my ecm (very easy) and shipped it off to RENNtech. They reprogrammed it and returned it UPS overnight. I reinstalled it (also very easy) buttoned up the motor and took it for a test drive. WOW WOW what a difference, throttle response and torque were right where they should be. The car drives like it should now, and I am VERY VERY satisfied customer. I highly recommend RENNtech and John Bologna, they do everything the promise and more!!

Tom Stokes
Posted By: RENNtech
Dear Mark ,

Just wanted to drop a quick note and let you know how happy I am with the performance upgrade for my ClS63 – you were awesome to work with and the knowledge on the product was first class all the way around – great precise instructions and complete ease on every aspect….really appreciate it and I will for sure be back in touch for the next upgrade (can’t ever have enough HP!!)

Best regards,

Posted By: RENNtech
Thank you George,

This is what I like about your company, you don't walk away from your customers..Take your time…I will only use the car next season as its getting hot now…so you have 3 to 4 months to work something out..

Kind Regards

Posted By: RENNtech
Mark S,

I just wanted to say thanks for the great experience with RENNtech and your assistance in making it so easy to tune my C 63 AMG. The fast turnaround on my ECU was less than 6 hours! I just re-installed and all I can say is WOW. Talk about waking a BEAST! Love it. I will recommend you and RENNtech to all my MB friends.
Best Regards,


C63 AMG (W204)
Posted By: RENNtech
Mark S ,

I just want to thank you for all your help with the ecu tune. From the first time we spoke you answered every question and concern and when I told you I wanted to wait to put some miles on the car you understood and didn't try to push me to tune it sooner. When I called or emailed you answered right away which made me feel comfortable as service is important to me.

The tune is super impressive and the difference is night and day just as you said. I thought the car was fast before but now it's just really fast! I would recommend RENNtech to anyone that is in the market for a tune and I'm sure you'll hear back from me when I get my next car.

Thanks again for all your help.

Ari R.

2014 (W212) E63 S Biturbo
Posted By: RENNtech
Hi Mark S.

Just wanted to thank you for all your help in getting the ECU upgrade to my E550.
The experience was great. I sent you an email and you called me the next day.
We made my appointment for couple days later and when I showed up you were there to greet me.
You explained everything to me and answered all my questions. The upgrade only took about an hour and 15 minutes.
What a difference in performance the upgrade has made.
I can't believe how fast my car is now…. almost too fast.
Still trying to talk wife into doing it on her S550…. will let you know if and when that happens.

Renntech should be proud to have you working there as well as you should be proud to work at Renntech.

I am beyond thrilled with the entire experience and tell everyone about Renntech.
If I come across some more money laying around, I will call about maybe getting the exhaust upgrade too.

Thank you so much.

Harvey B.

E550 Biturbo (W212)
Posted By: RENNtech
Good morning Mark S.

Just a note to let you know that I am very impressed with the ECU upgrades
on my C 63 AMG the and 430 CLK. The power increase on the C63 is awesome
with no loss in drivability. On the 430 CLK the upgrade got rid of the
hesitation in throttle response. Thank you for help and assistance.

Gary P.

C63 (W204) & CLK 430 (W208)
Posted By: RENNtech

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7825 SW Ellipse Way, Stuart, FL 34997
(+1) 561 - 845 7888
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7825 SW Ellipse Way - Stuart, FL 34997
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