I have a Z3 2.8 coupe with the 17 inch package and just did a heap of research before buying my BF goodrich KDW2's. If your biggest concerns are performance and price (as mine were) these are the tires for you. A hundred dollars per tire less than the Michelin's I originally had on there and the handling is just as good. Some people complain that they're a bit noisy due to the unconventional tread pattern, but I really don't notice it at all. And to be honest, anything is quieter than my worn out Pilot sports. The Michelins were simply driving me insane after just 15K miles, and I'm not usually one to mind road noise.
I've heard that the goodyears are a bit squishy on turn in, though reasonably good in the rain. Sounds like a lot of performance to sacrifice for an expensive tire. I've heard great things about the Kuhmo's, too.
Tirerack can ship to a wheel shop near you, which can save you a heap of money over the garbage they try to shove off on you (I had one guy telling me he could reeeeaally strech and give me the Michelin PS2's for $1,600...) Check out the 'certified mounters'