Gaining horsepower on any BMW really is an expensive process. You can upgrade some internals, you can stroke them (although the m54 not particularly good for stroking), or you can go forced induction.
Thats not to say their isnt a large aftermarket, just not for horsepower.
Oh and the US spec e36 M3 is totally neutered. Its like the sissy bitch little sister to its European big brother.
Last edited by DHK; 01-28-2013 at 12:57 PM.