Originally Posted by DaanBMW
As for the straights... the sway bar does not do anything in straights, it only works when an asymmetrical load is received by the springs (cornering, or hitting bumps with only one side on the car, or 3-wheeled inclines ;-) ).
When I took off the FSB on MK4 GTi, car felt totally different. Steering got way more feel, left the "boxy" feeling that you get when you turn the wheel. Had way more feed back through the turns. But it ate thru control arm bushings. Had to replace them every 30K or so. Auto-X'ers have told me that the car actually handles worse on the track with no FSB, but for street use, I would have never gone back.
I put a 28mm RSB on it, car handled like a dream. Front had lots of feel, while the back cooperated nicely. However, on a highway straights, back was very gittery from the thick RSB, due to restricting individual side movements of rear suspension.
My e90 currently does have good feel, due to having a balanced RWD chassis, but I can feel it could be so much better. With DTC on, back does slide out easily on wet surfaces. However, during everyday driving, I can feel the back end is a little "lazy". So that's why I am going after RSB to get the right feel. I know it's an expensive installation and want to get it right the first time...