Vmax is somewhere around mach 6 I think.
I think it's even less. X-15, the rocket powered experimental plane, barely reached Mach 6 despite trying hard to set altitude and speed records. Altitude record was about the same as here (slightly above 100km), but that plane looked like a missile, with very small wings and very fast reentry. Virgin Galactic doesn't look like a missile and has some special design to reduce speed on reentry, so it must be much slower.