It can do a lot of different things, usually one or more of:
* Remap the transition to favor high rpm before shifts instead of normally favoring lower rpm to save fuel
* Faster throttle response (it becomes “twitchy”, slightest pressure, lot more throttle)
* Change to exhaust sound
* Tighten the steering
* Tighten the suspension
* Remapping the engine ECU (valve timing, etc.) for more power
Latest Answers