Duncan Racing’s Fat Boy 4 Complete Exhaust System for the Yamaha Raptor 250 is said to give riders horsepower and torque gains up to 25 percent. It gets CNC-bent 304 stainless steel headers, mid-pipes and tail sections. Front and rear end caps are CNC-machined from 6061 billet aluminum, and the muffler mounts are CNC-machined from a single piece. All mufflers are completely rebuildable and repackable, and feature stainless muffler cores. The Fat Boy 4 comes with a free jet kit, and HQ Quiet and spark arrested mufflers are available. Get the full 411 at www.duncanracing.com or call (619) 258-6310.