Thanks, It is the Borla Cat-back system and I bought it from Quadratec I think. Shop around a bit for the best price though. I had (i thought) the same system on my TJ and it was much quieter. My JK has the 3.6 6cyl and for the first month or so I wasn't sure if I was going to keep it or not since it was louder than I expected. Now I love the growl of it and on the hwy you can barely notice it.