Think long tubes
After the cold air intake and gears, I found that long tube headers with proper X-pipe and good cat backs made the most noticable difference in performance. I did alot of other bolt-on's ...plenum and T/B, underdrive pulleys, and SCT tune at Steeda....all added a bit here and there..but the biggest kick (other than a supercharger, that may come in the future) was the longtubes plus the rest of the exhaust system. I also noticed improved mileage....as long as I didn't get on the peddal too heavy. Remember, the easier the engine can take air in and push it out the better!
2003 GT
K&N cold air
3.73 gears
BBK ceramic longtubes
BBK X pipe w/ cats
Dynomax cat backs
Steeda underdrive pulleys
Dragon Plenum and 75mm TB
SCT tune on dyno at Steeda
Cobra 13" brake upgrade and 13" rear upgrade
B&M ripper short throw
Aluminum driveshaft
Steeda sport springs
Illumina 5 way adjust. struts/shocks
Steeda 4 bolt C/C plates
Steeda X2 ball joints
Steeda bumpsteer
Steeda full length welded-in sub-frames
HD front swaybar w/ Steeda billet brackets
Steeda aluminum upper and lower rear c-arms
Steeda rear adustable sway bar
Nitto 555 extremes 255X45X17