thanks stewart, to answer your question, as far as i know my area doesn't have emissions testing, i used to have a 2dr tahoe with flowmasters, headers (don't know which brand they came with the truck), and no cats and never had any problem. i guess the headers will be more for sound than power. i have a k&n intake system and a diablo predator chip with magnaflow exhaust. i have no problem dropping $700-800 dollars on headers, but the kooks i looked at were ~$1400 and that was a little pricey for me. anyway, thanks everyone for the opinions