Non turbo horsepower mods

Can some one tell me some non-turbo mods that i could do to a mitsubishi eclipse 1998 rs to increase horsepower? Im going to see how much horsepower i can get on it without a turbo, also if anyone can give me an expected horsepower gain on the mods they list that would be awsome thanks guys I know a few mods but id like to have em all listed on here so i know what im looking at

:P

Theres not too many mods out there for your motor (420a) ...well not many that will seriously increase your HP/TQ.
Its simply not a powerful motor. Any mods (with the exception of forced induction, of course) that you do to that motor will likely result in single digit gains...