I got the 04 Impala SS. I put in a smaller pulley a 3.4, autolites 104 plugs, throttle body spacer, k&n intake, exhaust. What other mods you think will be effective. I recently looked into reprogramming my pcm...I am a little sketched out if I need to reprogram my security system...tell me what you guys think of mods and so forth =)