Direct Cycle Parts for slipons, free shipping, add to your cart to see best price, use forum discount.......HDFORUM10 I think it is, for $10 off too! If you like the Fuel Moto stuff, use their site.
I recently bought a pair of MUTAZU 4" Chrome Megaphone MF-06 Slip-On Mufflers Exhaust for my 2016 Road King for $175 on Amazon. Never heard of them before, but for $175 buck I thought what the heck. They have the best sound I have ever heard from a set of slip-ons. I only have a few thousand miles on them so I cannot tell anything about how long they will last or anything. But I would recommend them.