I got the drift kit today and another awd upgrade today.
I tried the drift kit on a rwd car first. The car (a 350z) was really hard to control. I could drift it by using the brakes to get the rear wheels to oversteer.
I put the drift kit on my awd skyline and got really good results. I was able to do some really nice feints and four wheel drifts.
For $10 the kit comes with some nice looking wheels mounted with non-replaceable hard tires. They have a lot less grip than the hard tires that come with the tire upgrade.
I run my cars on and rcp track. The track worked well with the drift kit; I had enough traction to control the car but could still execute drifts.
I didn't have any racing buddies to go against but I am sure 2 or more cars drifting around the track will be exciting.