Best bang for the buck is a power adder...nitrous, supercharger, turbos..if you can afford it. For the basic bolt on...gears, pulleys, timing adjuster, exhaust, intake...oh, and of course, Steeda Tri-Ax. Basically anything goes, visit some sites for information.
If you go with a power adder, plan on beefing up the auto.
www.steeda.com