if its a auto, you might want to get a tranny cooler if you drive your car hard, helps keep the tranny from getting too hot.

everything depends on your funds.

imo, because i go the cheaper route, get custom exhaust piping with a magnaflow mufflers, hi flow cat, d c sport headers and any cold air intake system.

drive for a while, you might need some suspension and brake mods next before you go any faster.