I've been on the market for a while for some LT'S headers and arh and kooks are the best I've heard of but I'm still having a hard time deciding what brand to go with and the difference
I can't speak on the ARH's with any authority, but I've had Kooks for a couple years now and I love everything about them. I'm sure some ARH owners will chime in.
I have ARH. The headers themselves are very nice though a pain to install. The kooks connection points with the mid pipe are a better design from a serviceability stand point. I have found ARH has grown too fast for their own good and their customer service is not great whereas every dealing I have had with kooks customer service has been pretty good. ARH is a bit cheaper though.