I found this information when I was looking for state laws concerning exhaust sound level and plate placement.

http://home.ama-cycle.org/amaccess/laws/result.asp?state=KY

You can search by state from the pull down. Sorry I could not figure out how to make it a quick link in the message I will try to fix it later but for now you can cut and paste to get the information.
Some interesting information such as the state of Kentucky does not allow aftermarket exhaust that has a sound level that is above the original. It could change your mind on spending $$$ for an aftermarket only to get a ticket along with the deal and have your local law enforcement include you in their ticket quota every month.

* Last updated by: bgordon on 3/26/2009 @ 11:20 AM *

New Hampshire is the same. No pipe other than stock, but the max Db level is like 106 in NH (pretty loud).
There's only one bike shop in my area that won't inspect ANYTHING with an after market pipe.
It's VERY rare to see a bike of any kind in NH with stock pipes here, though. And the Harleys are the LOUDEST of course.
They echo through the mountains. Even when the sound of normal traffic fades away, while hiking, the fucking Harleys are still heard from miles away littering my auditory enjoyment of the woods.
Pisses me off every time it happens. My GF is tired of hearing my ranting every time we go hiking.

* Last updated by: gumbybob on 3/30/2009 @ 10:46 AM *