I did the exact same thing 2 years ago. Not much in changes . So after that investment I told the wife the engine needed a tune up. Well several thousands of dollars later I am still messing around and still not happy. Pulled the engine with 20 hours on it this weekend to see a spun bearning :cry: :cry: I don't think you will see any gains until you get inside the engine and really make it breath Put a blower on it and tell the wife its a muffler!