I agree that around 0.035" seems to be the go-to measurement for the quench band depth. On my B20E, the Mahle pistons sit at between 0.018" and 0.022" below the cylinder deck at TDC. My understanding is that the original B20E head gasket had a compressed height of 0.028" which would put my quench band in the 0.050 - 0.046" range. Rather sub optimal. The thinnest gasket that Elring offers is listed at .85 mm (0.033"). If that is the compressed thickness (the catalog does not specify so I am guessing it is) then that would put my quench band at 0.051- 0.055". The thinnest gasket I have been able to find for my B20E is the Cometic at 0.027" which would bring my squish band down to 0.049 - 0.045".

I think the suggestion to deck the block flush or just a couple thou below the piston crown was based on the common Elring gaskets that are showing up, which can be in the order of 0.039" thick. IPD lists their Payen head gasket for the B20E as being 0.050" thick. You would not deck the block flush with the piston crown if you were using the thinnest Cometic gasket.

Clearly, if you are going to fiddle with the compression ratio and perhaps the quench band you will have to know the specifics of your head gasket.