Get forward
I agree with this being a rider control issue, not a track length issue. Watch some Bret Rasmussen videos as he talks about this a lot. The basics are as mentioned above. Get your weight/foot farther forward, and slow down. But mostly, get your weight farther forward.
I think that is why Rasmussen talks about it so much is because right after he says that, then skid-doo pipes in and says "look how far forward you can get your fee on the G4 chassis!!" And, actually, there maybe is at least a touch of truth there. During my G4 test ride, I rarely found myself putting my feet all the way to the front, where I put it there often on my Axys. I still like my Axys better, don't get me wrong, but it definitely helps ski-doo if he constantly lectures on that point, which he does.
Edit: One more thing. I'm going to respectfully disagree with what seems to have been insinuated above. I don't feel at all that I need, or even should have, a 163 instead of my 155 in order to continue to "progress" my riding. On the contrary, I think I'll progress my skills faster on the 155 as it will be easier to learn new things with a more nimble more agile sled. I'll just run out of juice faster on the few days per year that the snow is ridiculously deep. To me, that's the real deciding factor on how long of a track you should have is what is your average depth of snow you're riding in. As I understand it, there are some guys in B.C. that seem to get 3 feet of fresh every stinking time they ride. Lucky Jerks!! Well by all means then, grab a 174. For me though, I'm lucky to get 1 or 2 days a year that the snow is deep enough to have me wishing I had a 163. I enjoy having the more nimble and agile sled on all the other days when there is 2.5 feet or less of fresh powder.