sx 60
51.1 mph with the gp 460 backed the run with my gps, both speedo and gps read the same. the tanaka 47r will do 46.9 both have x can mufflers with internal baffles, elbows and silicone tubes, that reduced the noise, but still a little on the loud side. No db reading but sounds like aroud 90 db, I fly rc planes and they do a db reading before they let us fly so I have a couple of plane in the 90 db range and the bike is about the same. X can with no baffles no elbows, no silicone tubes is extreemly loud.