I have a yoshi rs4 full system on a 2011 yz45o with the arrestor factory installed. My question is will I really gain any horsepower or torque by removing it? Or just a louder bike? I would like to believe it was engineered for peak performance the way it is. But people have told me otherwise. (Not really trustworthy sources) I ride %95 percent mx tracks so I really don't need it forest approved.