The issue I'm looking to get resolved is....what happens, on short shifting below 4k rpm, all is well, depress the clutch, back off the throttle, revs die quickly, engage next gear, make progress.
Above 4k, it’s a different story, depress the clutch, back off the throttle, stays at whatever rpm it was at for perhaps a second and a half before the revs die away and hence you have to wait before engaging the next gear. So, fine and dandy for pootling about, but when in a hurry (and what are Sports cars about if not to hurry from time to time), not so good….if you forget in the heat of the moment and engage a gear, the rears spin up and dump you in the scenery.
To be fair, the Mustang is an auto, so the box sorts this for you....in a manual 'tis a different story....
