Bump to revive a useful thread again...
I have a 2000 323Ci that was purchased with 114K miles, (has 119K now), the factory sport suspension, a square set of ASA AR1's 235/45/17, and a custom exhaust. I recently replaced the suspension with an H&R Touring Cup Kit, including strut tower reinforcement plates (BMW Group up front, TMS at the back). The biggest impact was on the handling. I thought my Bimmer was good beforehand, but it is simply incredible now. It is very well cemented in fast, mountainous bends, is less dramatic in its dynamics, just sits in and grips. Responsiveness and communication through your butt and fingertips is also fantastic.
Ride is good, more connected, more controlled on the rebound. Considering the entire process (parts+install) set me back $970, it is a lot to ask, but the benefit is profound.
The car just feels more alive. It wants to be driven. I recommend it!