How much horsepower will I gain over stock with the following mods: SLP Loudmouth, Volant Cool Air Induction, ASP Underdrive Pulley's and 3.73's?

 

Probably around 20hp. 3.73's will not give you more hp but your car will have better accelerations (althrough each gear will be 10% shorter).

 

Headers 1st

 

yeah i see you're a ...you should prolly search that...it should be fairly easy to find...but whatever...those really wouldn't be my choice of mods...first off loudmouth is goign to suck if you ever get headers which i highly recomend...i don't know anything about the intake and you hsould just save up for a 12 bolt and put some 4.10's in there...underdrive pulley=good choice