Originally Posted by mthomas
So I am considering the hpa setup. This is on a 330xi which will see 1-2 track days a year, 1-2 autocross days a year. I enjoy pushing it in the twistys, but it is my DD. I am willing to give up some plushness in the ride, and enjoy the feeling of a tight, responsive vehicle, but do not want to end up with a slammed, back breaker. I was thinking of not changing the sway bars, and was not sure about subframe or other bushings. For this scenario, what spring rates do you think might be right. What is your opinion of the bushing issue? Harold felt that at 70,000 they are probably toast.
I would do exactly what cyniclaus has done in his post above (minus LSD).
The car needs stiffer bars, and yes, I would look at swapping the bushings while you're down there.
I think you'll be very happy with the results.