Sure there is and always be exhaust pressure left, but the question is how much? Minimizing it will get you an efficient engine by default, if there is too much left we are seeing that you can capture it with MGU-H, but this gives you higher MJ class (fuel penalty) when you use the energy to drive the wheels.
Throttle loses are only a small issue, because in a race the engine is running at WOT most of the time, if you have a slippery surface then for lower power you simply use lower rpm, but still WOT.
And very nice video of Audi telemetry, where you can clearly see that most of the time the engine is run between 4.000 and 4.500 rpm, over that line power is probably slowly dropping, this fenomenom can be seen in every diesel car, and there is not much you can do about it. I doubt torque is increasing over 4.000 rpm in that diesel engine. I wonder if this year they will be running lower rpm, is there any telemetry from this year?
There is no ranting that bigger is not fair, or higher rpm is not fair whatever gives them greater efficinecy and we will see what comes out
