Does anyone know if mixing after market exausts like a dyno port pipe and a SLP silencer will have negative results, or will it just change the sound? I have heard it will help add power, I've heard it will hurt and I've heard it will not effect anything anyone got any insight?

It's on a REV 800 with a remanufactured crank, if that matters at all, and its carbed not efi, or a variation thereof.