I just bought a 21 pretty much stock. S&S slip ons is the only mod it had. Sounds pretty good, will be de catting the header so maybe the sound will change a bit. On my 14 I had Fuelmoto 4” Jackpots, they sounded good but it would be as good with Rinehart, Rush, Vance & Hines… if you are riding and hear a bike you like the sound, ask the owner what he has.