The M5/M6 header manifold kit offers performance, quality and flexibility. With a specially designed expansion chamber, torque is increased dramatically in the low and mid range while giving significant hp increase throughout the entire powerband. The RPi header set allows the user to switch between the factory catalytic converter and the race pipe via a specially designed v-band clamp. The $6995 price includes a $1200 core fee which is refunded once the customer's original manifolds are returned to RPi in good condition.