Love 'em. I picked up a pair from the classifieds on another forum, and got the tuning kit from Supertrapp. With 14 discs and a closed end cap, I'm quieter than stock at idle and cruise. I get no loud overrun when engine braking, and they've got a nice, deep roar when I'm on it. Very ear-friendly, even with a Jackpot converterless head pipe. I may be giving up a bit at the top end, but the low end where I spend most of the time is stellar, and I'm not blowing out my ears or pissing the neighbors off.
And I've got an EPA stamp if anyone looks. I know it's not the way they're tested, but with a db meter on my phone, I measure 82db standing 20 ft. back and 10 feet to the side.
Sent from my iPad, probably while I'm pooping.