Hey i was just wondering, can we modify 2004 wrx (not sti) by using the 2003 wrx mod?? Like intercooler, exaust,bigger turbo, ect.........
it just somthing ive wanted to know

those are external engine components so i dont see why not.

The only part I can think of that might not fit is a front mount intercooler, because the bumper is a different shape. That might even fit though if you're lucky.