Just had a set of Dunlop Direzza Z1 Star Specs installed on my '05 Z4 roadster. Now rides like a completely new car. Much smoother ride even on what they call roads here in Dallas. The old Bridgestone RE050A RFT's rode like rocks. Now I see how long they last or don't. My next auto-x is in 10 days.
I have an 07 Z4 Coupe with Bridgestones, and I admit they are quite noisy, and I like your characterization about riding like rocks. However, I have Michelin RFTs on my 2010 328i convertible (Sport pkg), and they ride much quieter and smoother. Both cars share the same tire sizes. I'm sure much of the improved ride is due to differences in the suspensions, but there is little doubt significant improvements have been made in RFTs over the last few years.
I ran a set of the Dunlop Direzza Z1 on my e90. They are really sweet tires. Beware that they only last about 10,000-15,000 miles. I'm not an auto-xer but I drove the "Tail of the Dragon" 4 times with them in one year. They were absolutely AWESOME and stuck like glue.
Direzzas The thing about the Dunlop Direzza for autocross is that it has its best grip BEFORE it heats up, making it a great autocross tire. On the track, it tends to lose some of its stick as it heats up---the opposite of, say, the Bridgestone RE-11.
