i personally have a kamikaze 4-1 w/ 2.5" downpipe, on my rex...its ok. chromed out and all...no rust showing up yet and its been on for about half a year now. now as for the power gains with i ti think it may have hurt me more than helped but i wont know til i dyno it later today or monday. who knows though...they boast that it will give 5 more than a dc header...but yeah stear clear of the ebay shit. it will rust up on you really quick from what i have heard.