Dinan does great work. It'd be interesting to see if people can put down better track times with their slammed car. I'd guess not, especially on a non-glass smooth track. I remember a national champion autocrosser telling me once to "put the stock springs back in, BMW spent millions of dollars getting it right and you spent $250 screwing it up"
That is in my e36 M3. The only after market suspension I've owned that I really liked was the Dinan setup in my 335i, which was incredible. My ZCP M3 has a very similar feel in soft, and is a little stiffer in Sport, perfect adjustability and no need to change.
A lot of people underestimate how important suspension travel is.