If you just can't seem to get the wraith tank's lazy plasma shots to go where you want them to, do this:
First, make sure that you have a clear space for boosting in front of you. Then, boost and (at max speed) fire the shot. The momentum you had when you fired gets added to the plasma blast. Basically what this means is that the shot will go faster, which will make it go in a wider arch (straighter shots), and, with the wider arch, it can now go farther too.