You'll reduce the back-pressure in your exhaust system and getter better flow and a meager HP improvement. I'd combine that glasspack with a good header system for an additional boost in bolt-on HP- just don't expect a lot without head work, a cam, etc. Note that the exhaust sound will be louder and may possibly attract unwanted attention from the "law" when you get "on it." It may cost you a few bucks more that you're expecting.
Good Luck!
