had my m3 for a month now and i want to re-map the car but

[AsianMpower]

which company shall i trust and which to avoid?
i see companies quoting 20-30bhp and then others quoting 15bhp.
what is the truth? is it worth it or best to save more cash for other bits?
what have you lot done to make the car quicker?

[AsianMpower]

so is there other performance parts that are worth doing?
and when you say that the engine has power output from 325 to 340 does that mean that if a tuner was to remap an engine that proudces 325 he will be able to get the car back to the 338bhp figure quoted? plus the additnal 15bhp from the map ontop?