well thats if you dont get it tuned you lose hp, if you dont your stock map for the bike with the new slip on you will lose power, proven fact, seen it,tested it. I used to work where we had a dyno and we tuned 24/7. But if your getting a tune and mapped your good...should see about 3-4hp over the stock can and about 10 pounds lighter so only good ratio's coming your way.