The export version, the "Jaguar International" was marketed as a M1.6 aircraft but whether it ever achieved it in service, I've no idea. It did have a slightly more powerful engine and the intake was supposed to be good up to M1.8 but who knows? Some of the export customers weren't averse to flying enthusiastically and I can't recall them complaining about a performance deficit.
The Mk 106 might have been helpful in going to M1.6 but the approved financial case was predicated on reduced in-service costs so performance improvements didn't get too much emphasis (apart from easier AAR; needing PTR for some parts of the AAR envelope is a bit self defeating). ISTR that RR estimated almost 20% thrust improvement in the early days of the 106. I'm not sure what the final number was but single digit %age seems about right.
I think the M version was purely a French requirement.
EAP