Im with the rest on the SII2s, there a little louder than stock with a nice tone. Now I have Cycle Shack touring mufflers just a tad louder tha the SEIIs. but not a loud as the Rush mufflers with 13/4 baffels.
Supertrapp mufflers are only 3db over stock and are supposed to give about a 12% power boost. I just recently installed them and originally thought they were too quiet but I've grown to like them. Check out their website it's got soundbites and more info http://www.supertrapp.com/product_se...ycle/vtwin.asp
I have the Supertrapps also and they are nice and mellow with a deep rumble with true duals, but forget it if you grab a hand full of throttle they can get a little loud.