Also, don't be mislead, it has no packing in it, it just has a perforated core as seen in the pics, technically legal as it has a baffle, it's going to be loud. They make versions with packing, but I wanted to use this one
The muffler hes building I believe has a longer smoother reverse megaphone shape, packing, and I imagine will be a good bit quieter while still sounding aggressive, it may even make more power, because of the much longer megaphone portion, who knows!