EXCEPT ZR2 & AT4X models. Factory Split Rear Exit Vehicles ONLY. Add Adapter 60706 for Crew Cab with Standard Bed (6' 7") 157" Wheelbase vehicles. This Borla(r) system has a valve simulator to prevent the Check Engine Light from coming on. The 3.5" diameter into dual 2.75" system features Borla(r)'s aggressive ATAK(r) muffler and Polyphonic Harmonizer Technology which utilizes patented units that contain pipes of different diameters and lengths to create multiple exhaust notes that harmonize to deliver a clean, rich, full-bodied sound with no drone inside the vehicle. Replace the Polyphonic Harmonizer behind the muffler in this ATAK(r) system with muffler 60679 to attain the S-Type sound level (quieter than ATAK(r)). Tips NOT Included, reuse factory tips. Systems that include tips are also 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 Silverado or Sierra the power and 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.