The T-4 System is a tunable version of Pro Circuits more exotic Ti-4R System and includes the all new, sound-reducing RC-4 Resonance Chamber. Pro Circuit developed T-4 Complete Exhaust System with the intention of satisfying your motorcycles thirst for more power at a reasonable cost. It will boost your bikes overall power by not only adding raw performance but will also add power by shaving weight. The durability of the T-4 is beefed up by using stainless steel for the head and mid pipe. Pro Circuit stepped up the performance of the T-4, making it tunable by including both spark arrestor and race tip so you can choose your end cap to match your riding conditions. Lightweight 6061 T-6 aluminum sleeve. A removable U.S.F.S.-approved spark arrestor and race tip are included with every exhaust. Maintenance on the T-4 exhaust is simple with the bolt-on removable end cap. RC-4 Resonance Chamber to reduce noise. Billet aluminum mounting bracket. Meets AMA / FIM sound requirements. Note: The RC-4 Resonance Chamber, depending on year of your bike, might not be included with the system. The T-4 exhaust gives you the ability to take your dirt bike off the track to the unbeaten path with the U.S.F.S.-approved spark arrestor but, when you are on the track using the race tip, the T-4 will meet all AMA and FIM sound restrictions.