[Proven]

Since you went with the non-turbo model I'd stick to the basics w/ power adders.

-K&N drop in filter (let that engine breath a bit better)
-lip spoiler (make the car look better)
-and springs (increase handling a bit and looks)

If the car doesn't have leather and you want it call around for the Kat skin leather kit and install it your self (around $650 for the materials pre-sewn and not all that hard to install, I did mine)

Also be sure to check out Nasioc.com and rs25.com. There's plenty of goodies out there.