All M4 Quiet Inserts are compatible only with M4 Exhaust Systems that retain the quiet insert using a snap ring. All M4 Quiet Inserts are compatible with new purchases. If you would like to purchase a quiet insert for an M4 System purchased more than two years ago from STG the insert will only fit your system if it is retained using a snap ring.
All M4 Exhaust listings on our website list which quiet inserts are compatible. You can easily determine which quiet inserts are compatible with your M4 exhaust system by referring to your exhaust's listing on our website.
You can expect a db reduction that ranges from 1-2 db on a Stage 1 Quiet Insert and 3-4 db Stage 2 Quiet Insert. Please understand that every bike is unique which influences the db reduction of the M4 Quiet Insert from one motorcycle model to the next.
Important Emissions Notice to Customers in California
The State of California prohibits the offer for sale, sale, or installation of an aftermarket part, which alters or modifies the original design or performance of a motor vehicle's pollution control devices or systems, unless the aftermarket part has first been exempted from the state's anti-tampering laws and been issued an Executive Order (EO) number by the California Air Resource Board (ARB). Legal in California only for racing vehicles which may never be used, or registered or Licensed for use, upon a highway. Any California Residents who order this M4 Exhaust from Sportbike Track Gear llc agree they are doing so with the intention of using it on a closed course as outlined within the California Notice.