thats from their websight:
Question: Are MagnaFlow Performance Exhaust systems legal?
Answer: YES, all of our Cat-Back Exhaust Systems comply with most state and federal laws with the exception of the Magnapacks. (Please note, local laws may vary. Contact your local law enforcement for specific guidelines.) Our products are designed and tested to meet legal sound level limits; however, when used in conjunction with other products (such as air intake systems or exhaust headers), the overall combined effect might cause particular vehicles to exceed the allowable limits.
A new law (27150.2 VC) does not require police to use a sound meter to test for excessive noise. A citation is now based upon the officers judgment. Cited violators may have testing done at a smog referee station.
If you didn't find the answers you needed on this page, please send your questions to us at:
muffler@magnaflow.com, or call our Tech Line @ (800) 817-3930 and one of our MagnaFlow tech staff will help you.