What should I do first to my 325ic for autocross?

[JoeP]

In decending order of importance:

1) Anti-sway bars, preferrably adjustable.  You can easily change these yourself.

2) Shocks & "lower" springs.  Bilstein PSS9 or PSS10 if you want to splurge and have adjustable ride heights.

3) Better, wider, and lower profile tires.

4) +1" wheel diameter.