air flow/hypertech power perfomer... very good upgrades and cheap.. Exhaust is almost an opinion thing...depends on if you want sound or power, but always look to the typical flowmaster/gibson/borla, etc. Like i said..it depends on your taste, they generally ALL give about 10-15/15 Hp/torque ratings unless you can find something exceptional.
Lookin for about 300 hypertech/200-500 exhaust.... superchargers if you start to spend that kinda cash run ya a couple grand, but make sure you look into procharger, they seem to have the most bang for the buck..and almost ridiculously so. And always available is the infamous Nitrous. Hell you may be called a "cheater" but the Mustang eating your exhaust will be too far behind you for ya to hear him
Just my kinda two cents.