Somewhat related, when I bought my '05 E46M years ago, the '05 car's were equipped with the improved ZCP suspension. Changing this out to Bilstein PSS9's was a revelation. The car behaved so much more stable entering into turns, and the mid turn stability was much improved. Buying PSS9's was absolutely the right move for me. Next, I took it to a very good alignment shop; they corner weighted the car and completlely dialed in the car's alignment settings. The car turns in aggressively and what's more important, it always feels stable and confidence inspiring, meaning I can trust it in the corner.
Since then I have CSL bars and great tires in the Conti 5P in 285 (R) and 255 (F), which just adds incremental improvements that just makes the car more fun.