Borla® 400372 - XR-1™ Stainless Steel Oval Multi Core Rotary Engine Gray Exhaust Muffler (3" Center ID, 3" Center OD, 12" Length)

In racing, every horsepower counts, so no competitor will use something that will reduce engine power. Yet, winning drivers in all forms of racing use Borla XR-1 Multi-Core Racing Mufflers. It’s because these racers have found that Borla mufflers cost them no power and in many instances, actually increase horsepower. In fact, a Borla multi-core straight through muffler has actually been found to outflow a straight piece of pipe! Most of the recent Baja off-road endurance racing champions used Borla mufflers even though the rules don’t mandate them, because they either increase or don’t reduce power, and the noise reduction reduces driver fatigue and increases driver awareness.

Borla’s patented straight through, multi-core muffler design reduces restriction and increases exhaust gas velocity, making sure each cylinder is completely evacuated to make room for the incoming charge. This design absorbs the sound waves without disturbing the power waves, in contrast to the chambered mufflers used by most aftermarket companies. Chambered mufflers use partitions or baffles to subdue sound waves, which also creates backpressure and reduces power.

Borla uses austenitic stainless steel in the construction of the XR-1 muffler, which contains high levels of nickel and chromium, to resist corrosion. This material is harder than the lower grade stainless steel used by the OEM manufacturers, yet is very ductile. Nevertheless, the increased hardness requires special equipment to form and bend. The muffler contains stainless steel perforated tubes wrapped with several layers of stainless steel sound absorbing material and a layer of ceramic sound absorbing, high temperature material, all contained in a fully welded stainless steel shell.