that's drawing a pretty long bow mark,specifying that all modern gaskets are .2mm thicker than the oem?youve been busy measuring them all,and found them all to be consistant,ill bet you some are thinner or thicker and crush earlier,any after market gasket can be hit or miss,and have a softer or harder crush point,since asbestos is missing now they aint as hard and will crush more,i like to wind em down a couple more pounds anyway,ive reused head gaskets over and again with no trouble,oem and after market.
To date, since 2002, I have built over 80 motorcycle engines (and 2 USA car engines) using modern head gaskets. The brands are Vesrah, Honda (OEM, not made by Honda, BTW), Athena, CycleX, the red-packaged ones from Japan, and 3 other off-brands that seem to not have any brand name. All of their head gaskets are slightly more than 1.00mm thick, where their OEM versions were 0.8mm thick, give or take 0.1mm.
100% of the modern ones are thicker than the OEM Honda head gaskets on the OEM CB350 twin, CB360 twin, all of the SOHC4, the CB450, CB160, CB175, CA95, CA85, CB100, CB125, CB100, Kawasaki 650-4, 750-4, and a Kawi dirt bike (I don't remember its model), the Honda XL125, 250 (all 3 models), the CBX Six, and 2 Gold Wings (I don't remember their displacement).
This situation is true in all of these, so I surmise it is true in the entire industry by inference (it is even true in my Ford car engines). It is directly related to the loss of asbestos in head gaskets (and industrial high-pressure seal gaskets), due to international outlawing of it in the late 1990s.
