L (Long) NEW manifold allows you to increase performance at low and medium RPM for a better feeling. It is recommended for high grip tracks, top speed will be lower. REDS advise to use this manifold with REDS 2104 pipe.
M (Medium) is recommended for medium grip tracks where more bottom torque is required, top speed will be slightly lower.
S (Short) is recommended for medium or low grip tracks; it is a good compromise between torque and top speed.
XS (Extra Short) is recommended for low grip traction to achieve the highest top speed but lower bottom torque.