I put L A Chopper slip ons on and it sounds great. It has a nice rap between gears but isn't too loud at highway speeds. It actually sounds better the the ones I had on my 06 Harley Ultra.
I found my 02 Venture with 36,000 miles on clutch slipping after I went from synthetic Yamaha lube to a blend because the dealer was out of synthetic. Could that be part of my issue?