To complete this installation you will need to MODIFY the Original Equipment (O.E.) Mid-Pipe by expanding the outlets from to 2.25" to 2.5". This system upgrades your '84-'91 Corvette from the stock 2.25" diameter Axle-Back system to a more aggressive 2.5". The system features the classic S-Type sound with no drone inside the vehicle. It has dual BORLAÂ intercooled style 3.38" x 3" rectangle polished T-304 stainless steel tips on each muffler for a custom appearance. BORLAÂ Cat-Backâ„¢ & 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 BORLAÂ Sound of Power respected by motoring enthusiasts everywhere. Each system is built from premium high-quality 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. Best of all BORLAÂ 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.