The FMF Factory 4.1 titanium slip-on exhaust is the same exhaust that professional racers use to bring home championships around the world. FMF constructed the Factory 4.1 slip-on exhaust to offer the lightest weight titanium slip-on on the market. The titanium FMF uses on this exhaust is superior in quality and comes directly from the USA. The technology in the FMF Factory 4.1 slip-on exhaust cannot be found in any other exhaust on the market. FMF developed the proprietary Chamber Core. This FMF original core technology allows for smoother and more efficient exhaust flow to maximize the power output.x FMF developed the Factory 4.1 slip-on exhaust to be used for competition and this pipe is ready to take to the track straight out of the box with the AMA stamp of approval for meeting their sound requirements on most motorcycle models. The FMF Factory 4.1 has been designed to allow for easy maintenance with a removable sleeve for repacking. FMF offers the ability to fine tune the performance of the Factory 4.1 exhaust with the addition of tuning inserts and the option of a spark arrestor to give you no boundaries.