I'm quite confused with some of the posts here....I've never hit an asteroid (that I recall) and I don't think I've ever been hit by more than 1 or 2 shots from the weapons platforms.
I've gone wide and hit a gate before and also nailed the weapons platform on the inside of the track near one of the final turns, but never had a problem with other issues.
Here are some hints I can give:
1) You must LEARN the track (can take more than a few times). This includes learning the "racing line" of the track. The best path is NOT the shortest path in all cases. Bottom line, if you are having problems with a particluar turn, you most likely took the gate before that one at the wrong angle.
2) Make SURE you start the Cruise Engine with SHIFT-W (or the Cruise ICON under the FREEFLIGHT Icon).
3) I find it easier to to fly in MOUSE FLIGHT, but others may find it easier to use the other mode. Keep in mind that smooth and sweeping turns usually line you up with the next gate better than a sharp turn straight toward the center of the next gate as soon as possible (see #1).
4) Dexter screws up his run near the end, so there is NO reason to be in the lead....you will get a chance to pass him near the finish line.
I have no idea how anyone could be getting shot up (unless you are still in the starflier....). Hint: They sell the Crusader on the Battleship and it's most likely the best fighter you can have at this point in the game (and can easily win this race).
Hope some of this helps.