Borla Cat-Back and Rear Section 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 Sound of power respected enthusiasts everywhere. Each system is built from premium 300 series austenitic stainless steel; superior to T-400 series knockoffs; to give you the absolute best in performance and durability. Ultra smooth mandrel bends ensure maximum flow and power; and precision computer controlled CNC manufacturing ensures an accurate fit. Best of all Borla stands behind every system with a Million-Mile Warranty. Just what you would expect from the worlds most experienced and most winning exhaust brand. S-Type Cat-Back Exhaust System. Million Mile Warranty 1978 Porsche 928 4.5L V8 Automatic/ Manual Transmission Rear Wheel Drive (RWD) 2-Door.