That would technically be a critical though in normal cases (without the trait that improves criticals on grabs). Natural 20 + 11 (with traits). You are right with the math actually, but I meant non-criticals. Critical Holds, Double Criticals and Critical Success on Escapes always work. In the event of a Critical Hold Strength (even Domination, in my mind), a natural 20 on escaping still succeeds. That was mostly taking criticals out of the picture. So 19+11= 30 is the highest non-critical (unless a trait is acquired that alters criticals).