Go here:
http://www.enjoythedrive.com/content/?id=8132

Everything you need to know about legality and testing procedures, including references, as well as noting SAE test procedure J1169.

My friends and I have used information such as this to fight and successfully win judgments against exhaust tickets in the past.

 

I read in the link that motorcycles aslo need to conform to the 80db noise from the factory. Why are Harleys and choppers allowed to have a higher db then cars?

 

The simplest reason is that a lot of cops ride motorcycles themselves. I've gotten that answer a number of times from friends and officers that ride.

 

fujitsubo.

RRE stealth is also good.