RennTech Updated Program - 2016/2017
Have the Renntech cat-back, K&N Air Filters, and HAD the original RennTech ECU re-program, which all produced very satisfactory results.
I am running 20in Vorsteiners, with 295s in the back / 265s in the front, for as much grip as I can squeeze into the wheel well.
Renntech was kind enough, since I had my original program done late last year, to re-flash to the updated map at no charge (shipping of course, and dealer labor, which was like $70).
They turned it around fast.
Renntech recommended that a new spark plug
004-159-81-03
(I presume cooler) be installed with the updated map to get best results and prevent issues. This cost a few bucks (21 a piece plus install) , but went ahead and had the dealer do it.
I've been doing cars for 20 years. Lots of hopped up Hondas and Acuras. I owned a C63 AMG prior to the CLS. This single mod update may be the biggest "butt dyno" improvement I've ever felt.
It's absurdly more torquey across the low rev range, and it wasn't exactly a slouch before. It went from "I'm leaning back in the seat by using my right foot" to "had that extra bear claw for breakfest eh? Lemme squeeze that into your kidneys".
Bravo to Renntech for the power update.
Dyno trip forthcoming.
I have a 14 CLS550 4matic, and I'm looking at this tune
Is this the same one as yours?
If so, have you had any reliability problems with it? That's my biggest concern, too much power for a non-AMG platform.
I do not daily drive / commute my car often. Once a week maybe.
I've never had a single drivability issue out of it. No funny lights / smells / functionality loss.
I don't go beat the eyeballs out of it every time out either though. I had a C63 AMG, and it was driven like that, and the tires got expensive.
It's very drivable, like stock, with immediate power and throttle response. No issues keeping it at low RPMs. No trans issues.
I did have the dealership do all the work and preserve my warranty though, as insurance.
Wish I had the 4matic though...




