wel in your last question the answers are really self explanitory. i only wnetioned the exhaust cause i am tired of looking at it sitting in my back room. a full cat back will get you the most hp gains more times than not. but adding a muffler and having a custom cat back made will more than likely give you the same numbers all i was saying is why spend close to the same for a custom made exhaust that will probably sound somewhat decent but will not look or sound the same as a greddy or a tanabe. but it all comes down to personal preference and your money is yours to spend.