This Borla(r) Cat-Back(tm) system has a valve simulator to prevent the Check Engine Light from coming on. It was designed specifically for the 6.2L Silverado 1500 ZR2 and Sierra 1500 AT4X. The 3.5" diameter system has dual 2.75" turn down tail pipes and features the classic Borla(r) S-Type sound with no drone inside the vehicle. Replace the small muffler behind the primary muffler in the "S-Type" system with Polyphonic Harmonizer 60680 to attain the "ATAK(r)" sound level (louder than "S-Type"). Optional "True Dual" Cat-Back(tm) system available. Borla(r) Cat-Back(tm) & Axle-Back exhaust systems feature patented straight-through and multi-core technology to unleash hidden horsepower. Increased exhaust velocity adds power driving excitement fuel economy and the distinctive Borla(r) Sound of Power respected by motoring enthusiasts everywhere. Each system is built from premium T-304 austenitic stainless steel superior to T-400 series knockoffs (such as 409) to give you the absolute best in performance and durability. Ultra-smooth mandrel bends ensure maximum flow & power and precision computer numerical control (CNC) manufacturing ensures an accurate fit. Give your ZR2 or AT4X the sound it deserves bolt on a Borla(r). Best of all Borla(r) stands behind every system with a Million-Mile Warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.