your better off staying stock if your going to get them to make you a 2.25inch. you can ask Clifton, he accidentally went with a 2.25inch instead of a 2.5inch originally. do a 2.5inch from the cat all the way back to the muffler. if you get a 2.5 inch, expect to lose some throttle response, however you can also expect better gains above 4k, especially in lift. I noticed my fuel efficiency also got a lot better with a 2.5inch catback after about 2 fill ups.