Many years ago, I believe it was engine expert Clarence Lee who said that Fox engines felt like they were high compression engines when in fact their compression ratios were moderate. He said the reason for that was because Duke Fox made the rings round in the same fashion that automobile piston rings are made instead of the typical way model engine rings are made.
I have no idea how car piston rings are made but if someone in here knows the answer he could give us a clue.