Manufacturers seem to be trending toward putting more water cooled EGR back into the intake to raise intake manifold pressure, yet run higher dynamic compression ratio.

I do not claim to completely understand why Mazda emphasized that their header design allowed them to get to 14 to 1 compression, but they felt strongly enough about it to put it in writing.

The new I6 3L Hurricane +20 psi Turbo SO version runs 10.4 to 1 static compression with water cooled EGR AND water cooled exhaust manifolds,
but suggests using 91 Octane AKI gasoline.