For what it is worth the standard production Sea Harrier FRS1 would reach M1.3 in a dive wth no aparent handling or engine abnormalities. But please don't ask me to explain why that should be so! The Pegasus turbofan concerned had a bypass ratio of some 1.3 and the only doors in the intake were typical boundary layer bleed doors. The row of suck in doors (used at low speed) were of course well and truly shut.