Why 2.75 Inch piping diameter? After much research, calculations, testing and development JHM 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 RS4's free spinning and high-revving V8. They 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 B7-RS4 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 the X-Pipe also gives the 32-valve V8 motor a cleaner, more refined tone.

Parts Included: Our complete 2.75 Inch Cat-Back Exhaust System with dual 2.75 inch stainless steel piping includes the following:
- X-Pipe Section (Resonated or Un-resonated)
- 2x free flowing mufflers
- 4x 2.75 Inch Clamps
- 2x Rear Hanger Adjustment Clamps
- 1x Rear Section Adjustment Bar with Hardware

Note about build time and availability: MADE TO ORDER - ETAs can vary

Note: Vehicles with factory downpipes require ES#4446180