I Need More Hp

Hey i was wondering what my next option would be as far as performance upgrades. I have a 99 Yukon 5.7L with a Flowmaster 40 Series Exhaust, K&N FIPK Gen. II and want to spend under 500 for my next upgrade. what would be the most cost efficient way to get more hp for my car. I would like headers but i've heard they're a pain to install. Any input appreciated

I've been looking for feedback from anyone who's tried the Superchips programmer for these motors. I'm wondering what kind of hp increase, and what it does to temps. They claim a 40 hp increase or so. I know with the diesels, they get some real serious gains - up to 110 hp, but sometimes exhaust gas temps get a bit high, even with a high flow intake and exhaust. Anyone tried one yet?