Here's what I'd do... more or less in order of importance:
- Full tuneup + compression test (plugs, wires, air filter, cap, rotor, oil change, timing check, valve adjustment, full bottle of UTP on next fillup). Kit costs about $70 from Hawk, and UTP is about $3.00
- New gearing ($4-800 depending on how much work you're willing to do yourself)
- Header + 2" exhaust ($2-300)
- Cam ($100-200 depending on what RPM you want your power to peak at)
If you get the right header and cam, you can bring them with you if you choose to go to a 1.6L down the road. Gearing is SO important - even if you go to a 1.6L - a stressed motor prematurely wears quickly.
If I were you, I'd STRONGLY consider what tires you want to go with. If you have your heart set on 33+" tires - you may want to STRONGLY consider going diesel. If you do the diesel swap, you actually DON'T want to change your gearing at all!!! The diesels LOVE LOVE LOVE running at low RPM - even on the highway. 33/34" tires and stock gearing are PERFECT for a diesel.