This is for the OS91 3D SPEED ENGINE!

This tuned muffler has been designed for increased torque between 11,000~14,500rpm for OS and 12000~15500rpm for YS.

Over 15,000rpm on OS and over 16,000on YS has identical power to a conventional muffler.

With setting between 15,000~16,000rpm, drop in rpm due to steering load is avoided and normal rpm is maintained.

New version of Hatori's popular 9 series muffler, specifically tuned for the OS 91SZ-H engine, more mid range torque and higher RPM range to suit the new OS engine. Longer inlet section so is a good fit on the Synergy N9/Aurora. This muffler is almost identical to the Hatori SB-18.