The stickers that are being made are good for ~5hp. They are by far the best bang for the buck mod.
O.K. for real now. I personally have no mods on my car but am familiar with all of them that are currently out. I'd say the CAI is probably the best bang for the buck mod. It is probably good for around 5hp. Pulleys are a little expensive (I think $400+) but will yield 3hp or more and won't give you the extra volume like intakes and exhaust (if that is a concern to you). Headers would be awesome but the close-coupled cat may make that change impossible. It's rumored that up to 10hp may be hidden in the exhaust manifold.
I'm gonna be getting my car dyno'd in a couple of weeks so i'll be able t shed some light on this subject...all i have in right now is a cat-back and a pop-cone intake soon to be replaced by a Place Racing CAI,,,and the once I get the Unorthodox pulley's in i'm gonna have it dyno'd again.....
Black 2k SE Performance/package
17x7 Konig-Caffeine's ,Stillen front spoiler and pop-cone intake,Aluminum dash kit,Remote starter,35% Tint,Aluminum Pedal Kit,APC Super white headlights and fogs and front and rear turn signals,Ventshade-ventvisors,Custom Front Grille,Stromung cat-back,Place Racing CAI (in the mail)......