aw man, i didnt get to put my .02 in yet...
ALL HEADERS HAVE THEIR DOWNFALLS! the cheap slip fit headers are hard to install. the expensive slip fit headers are alright, but expensive. TOGs and S&S are the only non-slip fit headers. i have ran both sets and i like my S&S better.
SLP and SSAC have some retarded downpipe design with a weird bend that you WILL hit on things in the road and destroy it.
Pacesetters are okay, but the two into one design at the downpipe has got to be one of the dumbest things i have ever seen.
ZZP...i dont know much about them at all, but ive heard good and bad things about them.
TOGs are a REALLY nice set of headers, but the crossover can be slightly harder to seal if youre installing them for your first time.
S&S....well, super easy to install and seal.