Putting you engine at TDC and taking off a pipe to clean up you exhaust port is easy.
No gullible customers involved with my findings. Just a couple of guys racing for our shop back the seventies.
Trans sonic? Explosions have trans sonic pressure waves. What do you think pushes a bullet to trans sonic speeds? But let's just stay with sonic for now. A flow bench can't duplicate that either. Surely you must understand that flowing exhaust is much further from what actually goes on in there in a running engine than flowing intake.
I don't know about new bikes but back in the seventies a good port job made all the difference in the world. Granted, most of them weren't good but that is beside the point.