Doc 8168 Pt 1 explains the Category criteria well and they are purely a function of speed at the threshold, although the other segments will assume different speeds. The maximum speed for a course reversal for a Cat A procedure is 110 kts, however normally the procedure would be Cat A/B so the design would accommodate 140 kts - the Cat B speed. If you want to fly faster than that you'd need to follow the Cat C procedures (which are typically what you'll find in your FMS.)
Additionally, it states:
6.1.3 The missed approach should be initiated not lower than the decision altitude/height (DA/H) in precision approach procedures
This clearly indicates that initiating the missed approach below the DA will run the risk of infringing the protection afforded in the procedure design.