best N/A mod is the cams and manifold imo. I run those and man do they put out some power around 4krpm and up...very good mod and can be done for under 1000 when the proper time researched. I got mine from a wrecked s52 car.. I bought the whole head for 600 bucks and used the cams and turned around and sold the head for 450.. I already had the manifold though..