Dynomax 19391 Exhaust System Large internal flow tubes improve exhaust flow and reduce backpressure Exclusive patented flow director design channels exhaust flow and eliminates turbulence Fiberglass matting technology to absorb unwanted interior resonance while maintaining a mellow performance tone Dyno proven to flow up to 700 SCFM The "Pure Unadulterated POWER" of DynoMax Super Turbo mufflers are backed by a Limited Lifetime Warranty and exclusive 90-Day Performance & Sound Guarantee.