The Motordyne art test pipes where made through countless hours of research and development a new path has been explored in the never ending quest for performance. a method of directly altering exhaust harmonics for enhanced performance and sound, this is motordyne's debut of the patent pending advanced resonance tuning team. Up by 15 to 20 ftlbs more low end torque than conventional test pipes. Art pipes increase power and torque without the drastic increase in loudness normally associated with test pipes. these provide the quietest, smoothest, deepest sound while greatly reducing or eliminating rasp and drone. The difference in sound is not subtle. they're not conventional test pipes but motordyne art test pipes.