MBRP S6014AL: Exhaust System GMC Sierra 2500 HD / 3500 Duramax Crew Cab / Extended Cab 2006, Installer Series Cat-Back Diesel Exhaust System (S6014AL) by MBRP, MODERATE SOUND, 4 Tubing, Split Side Exit, and T-5053 Stainless Steel Dual Wall Angled Tips. Outfit your diesel pickup with a high-flow DPF (Diesel Particulate Filter - Back) exhaust system. Youll gain horsepower and torque, and improve your fuel economy at the same time. Youll also gain a mellow but authoritative exhaust note. Retaining the DPF means staying emissions- and warranty-legal for street use.