Piet,


A tuned pipe's boost depends on the 'blow down' period; not on exhaust timing degrees.

The degrees (with engine displacement and total system length) will determine the RPM at which the boost will be realized.

The blow down period is the period of time between the closing of the intake bypasses and the closing of the exhaust port.
It is this time when the fresh mixture ingested into the header, is blown back into the cylinder, creating a supercharging effect.

If the exhaust timing of that OS is 140º and the intake bypasses are open for 115º (boost port), the 'blow down' period is 12.5º.

This number is modest and is considered 'mini-pipe' timing. This is why this engine responds well to a tuned muffler, like the Nelson UltraThrust, or the JettStream.


It is not likely to gain very much more, from a full length pipe system.