Originally Posted by goriders
The best places to learn how to ski fast (in a straight line) are the landing portions of ski jumping hills. I am not advocating poaching these pitches!
Approach a local jumping hill in an appropriate manner (insurance, club memberships, qualified coach who will be present, etc) and let then know you want to practice your tuck for speed events and they may be willing to let you try it out. Most jumps in north America are under-used at best.
On a typical 90m ski jump, you should be able to comfortably go between 100-130 kph in about 6 seconds. Those hills are perfect for straight lining it as they have never been turned on and are designed to handle that type of speed and then let you bleed it off in a controlled manner.
Going anywhere near that fast on a ski hill run is asking for disaster. If you are in a low tuck your visibility is limited to what's in front of you and you can hurt yourself and more importantly others.
Basically, if you do this in a controlled manner you will go faster and have way more fun. Having an old set of DH boards with the edges dulled helps as well.