Hey welcome to the BMW world! if you want to see pretty much where bolt ons will take you we are finishing up an 04 M3 with active autowerke headers,exhaust, race software, AFE intake, and supersprint mid section. Car made 275whp with just intake/exahaust and 307rwhp after the headers/race software and midsection. I am also looking for one more person for a rediculously good deal on an AA supercharger kit for the E46 M3 if your interested PM Me or contact me in any of the ways below. I can also give you some pointers on what works best with these cars as far as mods.