I analyzed the last run where we had the massive backfire on the datalogger and I realized that 3/4 was short shifted. Short shifted means the upper window switch limit was not yet reached so only the clutch switch interrrupted the system.

Window switch is set to switch off at 6000 but he short shifted (he usually never does...) at 5700 so still full flow of 200 shot until he depressed the clutch. Since he is doing WOT shifts where a Traction control system takes care of bringing down rpms during shift could that have caused this massive backfire?

basically on passenger side head gasket completely blown, both head freeze plugs popped out and MAP sensor completely shattered. Manifold still OK though. Checked plugs, all of the light brown as it should be and color change on electrode just a tad before the turn - as it should be.