A stock Z06 would wipe the floor with the 911 turbo. Period. It has a 1.00g skidpad, I can't think of any stock car that has that. If anyone recalls, Road &Track had a roadtest at Thunderhill, about an hour from my house, and a place I race every other month or so. They took 12 cars, stock, a few Ferrari's, a vette, a 911 tourbo (4wd), a boxster, a some BMW Z3/5 and a bunch of other cars. I just had to post here because I saw the car that beat all of them today. The fastest car on the track was the 360 Modena, and second, and yes, second (ahead of the 911 turbo) was the z06. Impressive to say the least, best bang for your buck imo, although vettes have always had a very good bang for your buck ratio.
P.S. I saw the 360 Modena at the Le Mans practice/qualifying today at Sears Point today. It was beautiful, so frigging beautiful. Also there was a Testarosa (around a 88 or so), the muscle cars of Ferrari =), and a nice new 355 Berlineta. I think I saw a few Maranello's motoring around (the 550's).
Oh ya, and for 420k, you can buy a vette C5R, which has a skid pad of 1.44, a 1/4 of 10.3, and is just all around an amazing car, I watched two of them racing today. They sound amazing, there were a ton of porchses out there with them, and they were getting rocked.
Last thing I gotta say . I race go-karts on Sears/laguna/thunderhill, and buttonwillow everyonce in awhile, and our times versus these super cars are quite a bit faster. Eddie Lawson (retired champion motorcycle driver) would be mid-pack to a little back-pack with the Le-Mans cars, not the GT/GTS cars like the C5R, he would wipe the floor with them.