RE: engine porting
I was told by Dave Shadel of Performance Specialties that exhaust port matching (i.e. matching the muffler entrance to cylinder exit), would have no measurable effect...
...Unless, that is, the number of 20,000 RPM is significantly exceeded...
This is true even if the port in the cylinder casing is much larger than the muffler entrance (picture yourself the open exhaust stack of an OS.40-.55FX/AX/SX and the entrance to the UltraThrust UT-4 tuned muffler, or its spacer... It seems to offer a significant obstruction to flow, but it hardly has any effect).
As to the intake ports in the sleeve; in most engines, they are rarely matched to the bypasses in the cylinder casing, but as long as the sleeve port is larger than the bypass (no physical flow obstruction), I guess power gains from port matching at normal RPM, would not be large either.