Re: Quieter ride
Smoother tires are quieter.
A properly aligned and tensioned chain and sprocket especially with a soft(er) skate wheel can quiet the overall noise of the bike, as can dampening vibes in the fenders and chain guard with self adhesive weather strip lining the back side.
A mouse pad or similar glued to the right side gear cover quiets that area.
An intake dampener or air box of some sort will help considerably, make one with the most volume you can practically make.
After mufflers can be made to affix to the end of the pipe, but be careful not to over baffle.