The BORLA® system has valves. The system features polished T-304 stainless steel tips. BORLA® Cat-Back ™ and Axle-Back exhaust systems feature patented straight-through, multi-core technology designed to unleash hidden power. Increased exhaust velocity adds power, driving excitement, fuel economy and the distinctive BORLA® Sound of Power respected by automotive enthusiasts around the world. Optional 60707 resonator available for additional sound control. Each system is constructed from premium T-304 austenitic stainless steel, superior to T-400 series knockoffs (such as 409), to give you the very best in performance and durability. Ultra-smooth chuck bends ensure maximum throughput and power, and computer-controlled precision CNC manufacturing ensures a precise fit. Best of all, BORLA® backs every system with a million mile warranty. Exactly what you expect from the most experienced (and winning) exhaust brand in the world.