I have megaphones with SBD caps, its not obnoxius but it isn't quiet for sure. I'm planning to buy quieter silencers from Sean, but before that I tried if repacking makes any difference. I replaced original steel-wool kind, very airy stuff with FMF packing and it changed its tone a little to a better way, I just hope that FMF lasts there. Original packing maybe lasts forever, but it isn't good stuff if you want quiet ride.
Could that endcap itself cause sound, like whiplash almost? Because exhaust gases bumps to a straight wall (partly) because of the shape of the SBD cap.. Maybe it would make a little difference, if that straight exhaust hole has been machined in cone shape, so air could get out more smoothly?
Pic to get the idea (MAD drawing skillz)
