Full exhaust. I'm pretty sure they make headers for the 2.2 Eco.
Intakes are cheap to do.
Get good tires for those lightweight rims
I've been told the only 4 brands you buy are BFGoodrich, Goodyear, Michliene (sp) and Pirellei (sp)
Eibach, or Intrax spring to lower the car. Eibach drop you 1.2 inches, and Intrax is 2.2"
Get KYB struts for them too. You'll be happy.
Tint the windows, always a good mod
Tower braces and sway bars. They don't have to be done all at the same time. but they will help you out big time in the turns.
Check out my cardomain page to get more ideas. I have the 3400 V6 though