Weapon-R 4-2-1 Race Headers are designed with long primary tubes for high RPM power and stepped-sized tubing for higher torque gains. These headers are ideal for all forms of racing and are best for vehicles with high lift cams and a high RPM rev band. Weeapon-R uses a 2.5" - 3" collector for high exhaust flow and better performance gains. The catalytic converter is eliminated on all race headers.