They are suppose to be about 3dB louder than stock. I had them put on and Ican't really tell the difference in loudness from the stock mufflers. I got the two piece touring mufflers and have read that the single piece slip-ons are louder. Not sure if that's true or not. I'm thinking about going to Rush's with 1.75 baffle.
If you're looking for sound,save your money. I put a set on my 07 Road King. I couldn't really tell the difference between them and the stock mufflers. I've ordered a set of V&H Classic slip-ons. I may as well have put a match to the money I spent on the SE mufflers.
The older SE II slipons were pretty good.But HD has gotten out of the loud muffler business. The 07 SE II's suck! In fact, any muffler in the catalog with a green light symbol next to it or that says "street legal", stay away from if you're looking to make your bike louder.
put a set on my 07 ultra. i must of got a good set because they are definately louder than stock. many people will also tell you that they do actually get louder after they have a few miles on them. i got the one piece slip ons.