I still think this is really confusing.. Because I kinda want to read that quote in other way round, when using FP-DE pistons in 9.7:1 engine, you'll get 10.4:1 CR...
Not like 9.7:1 engine, and 9.1:1 with FP-DE pistons..
But basically this whole thing means, that FS-DE engines has different rod...