Was a little to loud for my liking just right now
The good: No noticeable loss of power to use the quiet core. Installs easily.
The bad, barely noticeable loss of noise. Big Guns are loud exhaust and would be surprised if it really did meet USFS noise requirements.
The product installs quickly and easily, however, it doesn't allow an aftermarket spark arrestor and end cap to fit flush. (Big Gun Spark Screen). I managed to make both fit, but the end cap sticks out a little.