Borla Boomer Muffler Thumper Oval 2-1/4in In 4in Side Round OutBORLA Boomers are full blown, high tech, dyno and race proven mufflers for the street or track. These eye popping, fully polished, T 304 stainless steel mufflers feature integrated polished tips, and utilize BORLA's patented race winning technology for improved exhaust flow. In addition to adding head turning sound, they also add a modest boost in horsepower. They utilize 100% welded construction for strength. High temperature continuous filament