The Injen Equal Length exhaust header for the Scion FRS and Subaru BRZ is the most important part of the stock exhaust system to replace since it is closest to the engine, and has the largest impact on power. The Injen Equal Length header follows the stock 4-2-1 type layout, but without a catalytic converter allows for more torque and hp. The Injen header maintains the stock feel of the N/A engine, but provides more power everywhere.