ON PYPES WEB SITE THEY CLAIM THERE RACE PROS ARE QUIETER THAN THEIR STREET PROS. ? WOULD THINK THE OPPOSITE. I WAS ALSO TOLD BY USING THE X OR H PIPE YOU WILL LOOSE THE SO CALLED RAPPING NOISE WHEN YOU BACK OFF ON THE PEDAL. ( ANY TRUTH ) THIS IS FOR THE STREET NOT THE TRACK. THANKS FRANK