if you're planning on
not doing a swap, it's probably best to do exhaust (including header), cams, EMS. intakes don't do much on an otherwise stock 5SFE. the factory cams aren't designed for revs, which is pretty much a requirement to make any decent power in a 2.2L n/a engine. once the cams (add headwork and oversized valves to help things out a bit) are done, you'll need the EMS to increase rev limit, and take care of the fuel and ignition maps. that's just a start.
FWIW, the power that most people get out of a 5SFE are eclipsed by a stock 3SGTE with a boost controller. not knocking it, but if you want more power, a swap really is the best way.
-Mike