What is the best ecu upgrade out there?

Welcome to the internet sport

Your options:

LET/Eurocharged
Renntech
Powerchip
Kleeman
I think AMS might do software as well

thanks!! i know its great!!!
how about you answer my question!

i know the options. any recommendations?

What would you like the upgrade to do? Raise the redline? Change fuel maps? Change ignition maps? Remove the speed limiter? Remove the adaptive throttle logic?

What modifications have you made and what impact do you expect a specific change to have?

I'd go with the big boys..

Renntech or Kleemannnnnn

Well a plus side to renntech is.. If you buy the RAT device (recommended) along with a tune. You can have your stock file and RENNtech tune saved to your RAT remote tuning device. Then that opens the door to having files emailed to you then loaded onto your RAT much like songs on a MP3 player. Via USB.. load and go... You can flash your car back to stock for dealer service.. then before you leave the parking lot flash your car back to the performance tune..

Now if you need a new tune for new mods.. RENNtech can email you the file, load and go. Their C55 tunes are rock solid.

true renntech is always a great product but the $ per hp is ridiculous.

I kind of wish now that I got the kleemann tune AFTER my header install so I could dyno them both independently but this saturday i'll see what the combined difference is.

eurocharged i gained 20 rwhp and 30 ft/lbs from my tune. and i didnt spend 3 grand to get it done

true but you're blown whereas our n/a motors we're hard pressed to see little gains. On the other hand, the c63 guys are getting huge amounts of power since they have basically detuned sl/s/e/63 motors...