Dinan is the most advanced research company in the BMW aftermarket. Winning back-to-back-to-back Rolex Series Daytona Prototype racing championships in 2010, 2011 & 2012 along with the top two podium spots in 2011 and winning in 2013 the grueling 24 Hours of Daytona as the engine supplier to Chip Ganassi Racing. You can rest assured that you are purchasing the most leading-edge technology on the market. Who else do you want to tune your BMW if not the company that beats the competition in power and durability in the most competitive road racing circuit in the U.S? What else would you expect from Dinan but the most technologically advanced exhaust on the market? The problem with most performance type exhaust systems is they compromise both flow and sound quality to try and achieve a balance between the two. Dinan's Free Flow Axle-Back Exhaust employs leading-edge technology to solve this problem with advanced features not found in most aftermarket high-performance exhaust systems, including a Helmholtz chamber and single-channel absorption increases flow while reducing unwanted noise and weight. The Helmholtz chamber is a resonance cavity that reduces the drone that most high-performance exhausts have at light throttle cruise. In addition, Dinan has a straight-through single pipe design to further reduce noise at light throttle cruise, so that it is a civilized exhaust that you can live with every day. The single-channel dual exhaust is a full 10 lbs lighter than the stock BMW part. The Dinan Free Flow Axle-Back Exhaust is a sporty sounding exhaust at wide-open throttle when you want it but also quite and civilized when you are at light throttle cruise. This is consistent with Dinan's core philosophy of "Performance Without Sacrifice". One of the reasons you purchased your BMW is because of its level of refinement. You won't ruin the refined characteristics of your BMW when you use Dinan performance products. This level of development takes time and is the reason Dinan is usually not the first company on the market but you will find it is worth the wait. Durability is also a primary concern at Dinan. Built from 100% 20 gauge-304 stainless steel to resist corrosion and backed by a 4 year/50000 mile warranty new car factory matching warranty, the most comprehensive warranty in the business and double that of our competitors' warranty (see Dinan Warranty Statement).