Air Intake(APS CAI + AVO silicon intake)
Exhaust(3" mandrel bent TBE)
ECU
Brake setup - Larger calipers with DBA 5000 + Ferodo ds3000
Suspension - Spec C strut or entry level coilovers (TEIN SuperStreet Damper)
ALK, RSB with Link, lateral links & trailing arms (maybe)
Larger injectors & fuel pumps (only if ur starting to run lean)

set aside some dole for blings like stereo HU, speakers, amps & sub (or neon lights ), engine bay dress ups and bodykits, etc.........

and if you're really serious and not broke by now, you can start playing with the engine internals such as forged pistons for higher boost.