BMW Repair: engine performance, k n air filter, compression pistons

Question
i have a 91 318is with a 1.8l 4 cylinder. i was wondering if there is a camshaft upgrade to be had. i can't seem to find one on the net or in any catalogs. is it possible to put a camshaft from a m3 in it. i like the car and the engine so i don't want to do a swap. i have a header, muffler. and a k+n air filter. is there someone that makes higher compression pistons and what is the highest i can go and still run on pump gas? thanks for ur time Jeremey

Answer
I don't deal with this aspect of the car, the money is in repair.
Checkout more of the e30 websites, their is bound to be someone out their that has tried this or other modds or could perhaps even tell you if this will work.
http://www.roadfly.org/bmw/forums/

http://www.bmwworld.com/repairs/e30.htm

http://www.bmwe30.net/
roadfly is most likely your best bet.
-cheers