My stock non-turbo MK3 with open diff drifts pretty good.
The near 50/50 weight distribution helps the MK3's stability, but you still need to fine-tune the suspension/alignment/camber etc to help. Other wise your car could become upset mid-drift because of minor bumps. Just be careful because such settings tend to make the car "twitchy" and you don't want to be breaking into a drift on a highway on-ramp... or do you?
First things first. Learn how to initiate a drift. There are several ways. One is to pull the e-brake while clutching, then drop the e-brake, give it some gas and dump the clutch to keep the wheels broken loose. Another way it to transfer the vehicle weight. Say you're going into a left hand turn; quickly turn the wheel a little to the left, then back to the right and the moment you feel the weight settle on the left side of the vehicle, very quickly snap the wheel back to the left and the rear end *should* snap loose, at which point you need to get on the gas and counter-steer immediately. All of this happens super-quick, so you need to be on your toes and practice practice practice. Also, practice transferring from drifting one direction to another seamlessly. From what I've seen, the judges like to see drifts initiated while still on the straight before entering the turn and continuing the drift into and throughout the turn. So I would also practice initiating a drift while keeping the car traveling in a straight line as long as possible, then allowing it to rotate and hold the drift throughout a turn/corner.
All much easier said than done. It's one thing to "power slide" and another to drift. Most people just give gas part-way around a corner to kick the back end out and think that is drifting. That's actually far from it.