Thanks for that impressive insight into the technicalities of the engine world !

If your memory serves you right the curve and drivability of a S2000R car is not that bad, with 2500-3000 rpm of ok HP and Torque.

Of course this will improve with 500 ccm more, but then we are talking a different ballgame. Not being able to crossuse btw WTCC type cars and rally cars. We are for the S2500 over to a V6 engine most likely, that few manufacturers have in stock.

I think the best way ahead is to go ahead and say that S2000 is the basis for the new WRC car, and if we need it to have a turbo, then let that car decide drivetrain ++ so it is dimensioned to take the power.
But I could also live with that S2000 NA will be top of the pops in the future.

Engineers are a strange breed, they can move limits - also for a 2 ltr NA engine !

In some years new ways of pushing our cars will be here anyway, be it Hydrogen cell, E-85 or something else !!

PS.
Would love to see a special class for McRae R4 type of spaceframe cars, also in Int rally, the sound must be beautiful !!