This new full system was developed for the Factory Yamaha YFZ450 racers: Bill Ballance, Pat Brown, and Travis Spader. Power delivery is strong and smooth with exceptional over-rev characteristics that make it pull harder and longer in the upper power range. This full system makes it easy to put in hard laps for an entire moto or a long off-road race. Recommended for use with GYTR Jet Kit, High Flow Air Filter, Billet Air Filter Adaptor Plate and Performance CDI. Features include: Hard-anodized aluminum muffler shell New cone-style end cap Spark arrestor Second option of Titanium tubing also available Uses stock head pipe heat shield Completely rebuildable Meets AMA® 102 dBA requirements Fits '04~'08 YFZ450 GYT-5TG93-70-SS *This accessory may be restricted to closed-course use. This accessory affects emissions; installation on EPA-regulated 2006 or later models constitutes unlawful tampering except when used solely for closed-course competition. This performance accessory does not meet California standards for off-road recreational vehicle usage regardless of model year.