The shortest distance between two points...

[Paul F]

AND  NO, NO, NO free-porting a "piped" engine is sure DEATH for the engine!!  For the pipe to work right, the engine MUST NOT free-port. Pipes use BOTH sound waves and pressure waves to work their magic.  Free-porting would destroy how they work.

Best Regards    TORQUE

Sound waves are pressure waves.  I think you meant "and resonances".  Resonances being the frequency that a specific volume of gasses wants to resonate at a certain set of conditions like at a given temperature and pressure.  Like the natural frequency of a whistle or organ pipe.  Those conditions (operating conditions) are very dynamic in a 2-cycle so there in is the challenge.