The Weapon R 4-2-1 race header for the Scion tC features a long-tube design to maximize high-RPM exhaust flow and a stepped tubing for higher torque. The elimination of the catalytic converter makes the Weapon-R Scion tC race header an excellent addition to any race-ready tC. The Weapon R 4-2-1 Scion tC race header was designed with extensive research and development as well as precision tuning on the Weapon R’s own dynometer. Weapon R has measured huge gains of torque with only this header installed. As this part will delete your factory catalytic converter, it is not recommended for use on public roads. A check engine light is to be expected.