BORLA XR-1 Raceline products are the choice of todays hottest drag and oval track racers. Featuring a patented uninerrupted-flow design and multicore technology. BORLAs XR-1 mufflers actually outflow a straight piece of pipe in repeated testing. XR-1 race products are light weight and constructed of high quality austenitic stainless steel for track-tough durability. They meet the strictest noice requirements and use sound absorbing stainless steel pcking to protect against burnout. Hands down, BORLAs XR-1 Raceline offers the best balance of sound and power.