Why does the yb engine seem to need to be low comp when running big power?

As far as i can figure out it must have something to do with the bore being so big, as the rod stroke ratio is only 1.66 so the piston is not at tdc for a very long time.

IIRC the rs500 touring cars had a comp ration of 6.8:1. Was this so they could run 30psi+ of boost and loads of ignition timing and still be reliable?

Or did the ecu`s at the time have a poor resolution meaning the low comp was essential?

also If there were to engines of indetical spec and boost pressure, The only difference is one has a comp ratio of 7.5:1 and loads of ignition timeing. The other engine has a comp ratio of 8.5:1 and less ignition timeing what would make more power?

There is alot of other variables that i would like to discuss but i thought that this would make a good starting point.

Please dont turn this into a high comp vs low comp thread as clearly the ideal comp ratio will be different for every engine.