Yea when you think about it the 5.2 Voodoo is 526hp with 5.2L and that is 101.15 hp/litre. The BMW E92 M3 with its 4.0L V8 made 414hp with just 4.0litres that is over 103hp/litre. Both these engines have one thing in common...rpm. Its going to take more rpm than the 7400rpm we currently have now. The Bullet is getting close with 96hp/litre/I don’t know where they will get the HP from without it. Cams add a few horses but there are compromises even with VVT.
There is not much room left.