Why 2.75 Inch piping diameter? After much research, calculations, testing and development we found that based on the 4.2L 32v V8 engine's demands, 2.75 Inch piping diameter is the optimal size. With a 2.5 inch exhaust you end up choking off the RS5's free spinning and high-revving V8. We have also found with a 2.75 inch cat back that torque is not sacrificed for power gains in the top end of the RPM band.

Why an X-pipe? Naturally Aspirated V8s always make more power with an X-pipe. The location and size of the X-Pipe in the JHM B8-RS5 Cat-Back Exhaust System has been meticulously researched and developed to produce the best scavenging of the exhaust pulses coming from either side of the motor. The location of our X-Pipe also gives the 32-valve V8 motor a cleaner, more refined tone.

Gasket Matched Flanges: The stock headers on the B8-RS5 are a LARGER diameter than the stock downpipes. This creates a flow restriction and hinders performance. This is because the exhaust gas is forced into smaller diameter piping. Additionally, this transition from larger to smaller diameter piping is not a smooth transition. The smaller diameter of the stock downpipes introduces a wall that the exhaust gasses must first run into before being able to transition creating turbulence. With our JHM Gasket Matched Flanges and the larger diameter of our 2.75" exhaust piping, there is no longer hindrance in exhaust flow allowing optimal exhaust flow for optimal performance gains.

Downpipe and Cat-Back Weight: The full weight of our exhaust system for the B8 RS5, Downpipes and Cat-Back is 69lbs. The stock OEM Downpipes and Cat-Back weights 78lbs

Not for sale or use in the state of California on any pollution-controlled vehicle as per the California Air Resources Board.