ATAK™ Dual Rear Section Exhaust System (11860BC) by Borla®. Muffler Sound: AGGRESSIVE SOUND. Split Rear Exit. 2" Tubing. Black Round Tip. Tip Outlet Diameter: 3.5". Tip Length: 8". When you want the best performing, best sounding, and highest quality exhaust system, you want Borla. Borla straight-through, multi-core ATAK mufflers and mandrel-bent exhaust tubes are custom tuned to deliver the most horsepower possible, with the most aggressive sound of any Borla system. And the quality, aircraft-grade, austenitic stainless steel construction allows Borla to back every Rear Section system.