I think you'd be better off getting your stock y-pipe optimized and getting a hi flow cat or just having a straight pipe made to replace your cat. Would be cheaper in the long run and from what a lot of people on here have said it seems the optimized stock y-pipe gets comparable or better gains than the aftermarket ones. There's a how-to floating around somewhere for optimizing the y-pipe. If you can't get a muffler place to do it because of emissions laws take it off and tkae it to a regular weld shop. Shouldn't cost more that 80 dollars from what others have said.