I think a chip to help firm up the shifts would be a good place to start.
If you concerned with just down low, then an underdrive pulley and optimized throttle body will really give noticable improvements. Cam gears will help alittle too.
Intake and exhaust are good for mid to top end power.
That's about where the bolt-ons stop and real serious modding begins.
An ATX cooler is highly recommended.
