check out the vendor reviews forum, it's pretty spot on. i've personally had really good experiences with MPJ Performance (a vendor on this site) and Gruppe-S. as far as companies that actually manufacture performance parts, i think there was another thread open on a very similar subject. someone please correct me if i'm wrong, but arround here there seems to be a pretty strong consensus that Perrin, Cusco, Cobb, Prodrive and of course STi make pretty good products. i'm sure that there are more that i'm leaving out simply because i can't think of them off the top of my head, so feel free to add more to the list.

 

mpj and subydude are my two favorite vendors