this is a sound clip of my new fullsac sportpipe with the cvo baffle recore in 2.0 inch. just for kicks and giggles, i downloaded a db app for my iphone (db 10th) and placed it 6 feet directly behind my bike and did a db reading. now this is not scientific at all, i have a shed on one side and a car parked on the other so i'm sure my readings were higher than they should have been. nonetheless, i was reading a pretty consistent 83db at idle, and 86db at 2500 rpm (with peaks up into the low 90s, but those were just quick spikes). so the pipes are pretty quiet, but they have a nice deep tone to them, and are very radio friendly when riding. i am a very happy camper 
fullsac.mp3 on the sound file, i take the rpms up to 3000, no db reading done though.
In States ike New Hampshire, the SAE J2825 dB test must be passed when getting and Inspection Sticker
Here is how it is performed.
How to Perform a SAE J2825 Motorcycle Sound Test
8 Ft Radius Circle
Meter at 45 degree angle and 20 Inches from Exhaust
Idle (1,000 rpms) - Max 92 dBs
At Spped (2,000 rpms) - Max 96 dBs
Would it pass NH State Law?
Maine's Noise Law is vague. And LEO can stop you and issue you a summons for Loud Noise, based soley on his or her hearing.
I would love to install different Slip-Ons on my SERK, but not worth it to me to run the risk of a $132.00 Fine every day I ride it.
So far the only Pipe I have seen that would probably pass is the SuperTrapp Stout 4", listed as SAE J2825 Compliant
S& S has one that says it is EPA Compliant