Performance chips... what do they do?

[j.fro]

I'd like to add Softronic to the list of ECU tuners who have a product that works. However, like the others have stated, ECU tuning alone won't add up to much of a difference. You've got to open up the exhaust and intake for an ECU tuning to make much difference...and even then, it may not be as much (or in the power band) as you hoped. And, after all of these mods, drivability will suffer. You're getting into racecar territory, and FAAAAR away from luxury touring.
Loud!
gains at 4000+ RPM
possible losses below 4000
kiss gas mileage goodbye

[eightsandaces]

IMO, if you want a good mod you will feel, get the underpulley.