A couple friends have taken their slip ons off the bagger and drilled a 3/8" to 1/2" hole in the front end of the catalitic insert. Sounds nice and quiet at idle, but comes alive at throttle. NOTE: These are not anywhere near as loud as SEs, V&Hs, Reins, Wild Pigs, etc. BUT, the price is right. (free).
After your friends get thru kidding you about your new mufflers, you can't go wrong with Wild Pigs. Search exhaust thread for great advice from various members. Wild Pigs w/ SMALL inserts are 90dBA at idle, which is exactly twice as loud as stock. NEVER change out the pipes and air cleaner without retuning, PCIII, etc.