Hello and welcome.
I would skip the intake kit for now, unless you're going for a very good one because there is a lot of cheap and middle-range stuff on the market that look awesome but lacks a proper heat insulation and you can end up with the engine breathing warmer air than with the stock one, with loss of power instead of gain.
I've got the same car as you, a 04 DE, and fitted a Cobra sport exhaust with hi-flow cats and installed a plenum spacer, a k&n panel filter and put in the airbox the velocity stack that comes factory fitted on rev-up and HR models, plus obviously a remap. The car gained a bit of peak hp (the dynamometer shows 280hp at the flywheel but my car's got 144K on the clock, in your case should be some more) but you'll feel the real difference in the middle range, there it gained 18-20 hp.