In Hong Kong the Ocean 2A/B departures state Max speed 250/ blw 11000 (eleven) feet.

In addition there is a speed restriction until the first turn Porpa in one direction and something-or-other when departing 25L.

But here's the skinny poop, if you do 250/110 even after being approved high speed, you jam the departure corridor up like an airplane-lav after a code red.

Most heavy jets fly better in a clean config. For the 747 classic, V2 +100 is around 288 and in the MD-11 the VCL speed is about the same.

So the next time you're approved high speed, it is mostly to get you out of the terminal area as soon as possible so as to launch more jets into the departure funnel.

On the MD11, at max gross weight you can make Envar (the FIR between Taipei control and HKG) at FL290 by maintaining 310 kts after Porpa then ECON climb out of 10,000 feet which is usually 355 knots.

I guess the the only caveat is hopefully the birds aren't filed for the same departure route.

FF