Yes, rear bushings are more important then front. If you don't want to go with poly bushings, you also can put RTAB limeters like those:http://www.vorshlag.com/product_info.php?cPath=0_1_4_155&products_id=59
Make sure that your OEM bushings are in good condition or just replace for new ones
Front number 9. You need to buy one with the hole in a middle, so your wheel goes back(less caster) and you have more space in wheel housing to put bigger wheel or to drop the car more with no rubbing issues
I would go with rear RTAB black bushes(only replace 2 bushes) and stay with standard suspension. You'll feel a bit more vibration then you drive normal roads with rough tarmac, but not too much difference
With standard RTAB bushes your toe can go up to 20mm in and out in hard corners. Car becomes very unstable and loose a lots of grip. If you replace those bushes to black Powerflex, only experienced BMW mechanic can see the difference. They are not metal, and I'm sure they are legal in all...
neither of this will benefit the most.
First what you need:
1. Poly bushings (Powerflex)
2. Track alignment (as much camber as you can dial)
3. Proper suspension setup(balance front and rear spring rates)
4. Better suspension (PSS10 will help)
There is not so much difference between PSS and...
This car on the video has KW Competition 2 way suspension (custom tuned for me), powerflex bushings, Recaro Pole Position drivers seat(passenger seat is stock) and Endless brake pads. Other then that it is all standard with no chip no big brakes and all interior in.
With passenger, Kumho V70...