Running with no mufflers is not the same as running mufflers with no baffles. Due to the relatively short design of the stock heapipes performance will greatly suffer especially at lower RPMs when there is low exhaust velocity and unless you add some length to the pipes there is also a very good chance the exhaust valves could be damaged due to excessive heat caused by direct reversion in the exhaust system

 

And you wonder why they are cracking down on loud pipes. Some people don't have a clue.

 

Sure you can do it. If you have too many horsepower in your motor, this is a cheap and easy way to let some out before they get to the rear wheel. You might also want to zip tie a sweatshirt around your air cleaner. No ECM download is necessary.

 

Thanks fuelmoto form the honest answer and not a wise a$$ remark. To bad people have to weed thru the replies just to get honest answers here