I just bought a kteller 2.5 in downpipe for my d16z6 greddy kit and i like it. The only thing i don't like is the fitment to my cat. I had to really yank it to make it fit. I also needed a gasket for it that didnt come with it, which i dont have right now, but i'm running it open for the meanwhile. But all in all it runs a hell of a lot harder. Power i know for sure i gained even on top end. Before i had no top end and shifted like at 6k rpms cuz power dropped off at that rpm. I havent dyno'ed it yet. Now i feel power all the way to redline. Im gonna post up pics as soon as my friend sends me the pics that he took the day i installed it. For those who want to get a downpipe for your greddy kit i would recommmend it from kteller or if not make ur own custom one to eliminate the elbow. Thanks to the peeps from kteller great service, got my downpipe 1 week from the day i ordered.