I got an HS-50 new in 1978 when they became legal in MD. Rode it for a few years, even commuting when I thought it worthwhile vs. my Chevy Nova (which might have been slower still). After a few years, I decided to have fun with it. I stripped off a lot of stuff like fenders, installed "drag bars" from a motorcycle shop, and foot pegs on the back axle so I could ride lying down. Installed a SuperTrapp muffler, polished the manifold (uh, mono-fold?) and matched it to the carb and made my own low-restriction air cleaner among other things. Mounted a tire-drive speedo and roughly calibrated it. Got up to 52mph indicated on the flat, and I'm hoping that soon my hearing will return to normal. I think it's still in a nephew's shed.