2000turbosi

I was wondering if anybody out there has any suggestions about these different mods with a b16a engine? i have a 2000 si with a drag 3 turbo set up, fluidyne radiator, urethane motor mounts, traction bars, inline pro head gasket, inline pro cam gears. I thought with the head gasket and cam gears this would save me money by allowing me not to rebuild the bottom end? if i invested in camshafts or valve springs would this add horsepower or would it mess up the setup i already have, i.e. the head gasket and cam gear lowers compression to 9.1 ratio? should i invest in boring out my head? placing stronger rods and pistons in the engine? ive already bought the vafc, 370 cc injectors, and fuel pump in order to take my car to get tuned, but im concerned with mods that give good horsepower and are a good pricel. i was also wondering if i would see any gains from these: larger intake manifold, larger throttle body, full 3 inch exhaust and removal of cat (3 inch). im new to the import scene so i would appreciate any help. thank you very much.