so first of all i don’t really know how much horsepower your BMW has, but to start with you should have about 400-600 Horsepower.
When it comes to the tires, you should definitely go for the most garbage one they have, so probably street tires. You want to have bigger tires in the rear than in the front, the rim size doesn’t really affect drifting in my opinion, so take what ever you want i’d say.
When it comes to the bodykit, you can pretty much take whatever you like, keep in mind that a drift car has to be light though. I don’t use spoilers very often, because most of the time i don’t really feel the need of a spoiler to press my rear tires down and give them more grip. Don’t get me wrong you want grip on the rear tires but not too much that you stop drifting.
So here comes the more difficult part: tuning setup,
Front tire pressure: 32PSI (You want a decent amount of pressure in the front tires, because they won’t get as warm as the rear tires. Even though you can’t see the tire heat, it still exists, you can look it up in the statistics for example.)
Rear tire pressure: 22 - 27PSI (This setting depends on how much horsepower you have and how much grip the car possess, choose low PSI if you feel the need for more grip.)
Drivetrain setting: Depends on in what gear you want to drift most of the time, but you should go for short gear ratios. Your car should have the capability to rev up pretty fast in the gears you want to use.
Camber: -3 - -4 degrees in the front and 0 - -1 degrees in the rear.
Front toe: only a bit, 0,8 degrees max.
Rear toe: only a bit, -0,8 degrees max.
Front caster: 7 degrees, max that out.
ARB front: you want to make it a bit stiffer than the factory setting.
ARB rear: you also want to make them a bit stiffer than the factory setting, but keep the front stiffer than the rear.
Springs: you should make them a bit stiffer than the factory setting, keep the front stiffer than the rear(most of the time i add 16lb in the front and 12lb in the rear).
Height: you want to put the car down as much as possible, but keep in mind that you don’t want to scratch the street with your bumper, if you do: put it up a little bit.
Rebound/Bump stiffness: you want to make them a bit stiffer than the factory setting, keep the front stiffer than the rear!
Brakes: depends on personal preferences, you can make the normal brake behave like an e-brake for example, but i recommend leaving this setting stock.
Differential: Acceleration: 100%; Deceleration: 100%; you want a locked differential.
So that’s pretty much it, hope my english wasn’t that bad (english is not my mother tongue =/ ) and I hope I could help you a bit.
I took all my “knowledge” from: Basic Drift Chassis Setup
make sure to check out the link if you’re interested in a more detailed explanation.