99 sierra - best power for your buck?

What is the best upgrade for under $1000 for a 99 sierra 5.3? Besides a cold air.

Without any other mods,the standard High performance chip upgrade (GM computer programer) www.hypertech.com (http://www.hypertech.com) will give you a part number for your truck, then try eBay for a good deal on a used one. Be sure the VIN is unlocked on any used programers. For more detailed computer tuning on modified engines, you'll need the www.hptuners.com (http://www.hptuners.com) programing tool or an experienced technician with the tools!