BORLA's XR-1® raceline products are the choice of today's hottest racers. Featuring a patented uninterrupted-flow design and multi-core technology, BORLA's XR-1® mufflers actually outflow a straight piece of pipe. XR-1® race products are made in the USA and constructed of high-quality T-304 stainless steel for track tough durability. They meet the strictest noise requirements. Multi-Core, Collector, and Bullet Racing mufflers feature steel wool packing for sound control. Sportsman mufflers feature high temperature continuous filament fiber (CFF) for sound control. Hands down, BORLA®’s XR-1® raceline parts offer the best balance of sound and power.