Ive read some guys on SRT8 forum running the headers Im going for and they've got great reviews, will be tricky to see how the bolt up to stock cats/mids, maybe upgrading those wont be a bad idea.. I dont care how loud my beast gets, actually the louder the better. My XK is registered in Fla who has no emissions so thats not of concern either or legality of the sound, hahaha