I started with a 22mm rear swaybar. Then added the Madness cold air intake, then 15% pulley, colder spark plugs, shorter belt. When the stock exhaust goes, I'm going either JCW or Miltek exhaust. Tuning would also be highly recommended.
I would suggest, if upgrading the HP on your motor, you should also consider suspension to balance out the chassis/power combination. I would also consider better brakes if you have the stock brakes. Sometimes I feel I could use a bit more stopping power.
15% reduction pulley (plugs and belt also), RMW tune, RMW street cam, larger injectors (e.g. 440s).
I would not spend money on a catback or a CAI (a higher flow filter would not hurt though). With my few mods (15%, CAI, RMW tune, that are getting me 200hp with no increase in redline), I am leaving power on the table with the stock injectors.
The money you have left over should be put into the suspension.
