Did you notice a drop in fuel ecomony immediately after the swap -- or was it so negligible that you didn't notice?

Do you still have your original rearend?

 

Yes, I did notice a slight drop in economy. I was in the middle of a 6 week, 9,000 mile road trip when I made the change and I could see any changes pretty easily. I went from mid 26 mpg to pretty much even 25's. Keep in mind that this was with a heavily packed car doing mid 80's and sometimes (often!) higher mph all day long.
As to any differences from the swap? Yes, I gained back 2/10ths plus in the quarter mile that I previously lost by going from 17" to 18" and much larger rubber. I don't have a definitive change because I only had 5 runs before the really hot weather closed in on us out here in Arizona. I (and others) can lose 2-4 tenths and more when the ambient air rises above 100 degrees and I quit testing/tuning at that point until the fall. Well driven C5 vettes were in the mid to high 14's my last time out when it was 108 degrees @ 7pm. I am anxious to get back to the track in another month or so and really pin down the improvement(s).
No, I do not have the original rearend, Regards, Jim

 

I bought a black Touring Auto and I love it. I drive a stick in my BMW328i and living in Los Angeles the stick is a royal pain. Traffic here is like nowhere on earth. the auto was the move. I love sticks but not enough to torture myself in traffic. I drive the car everyday and not a day goes by in LA that you don't have bumper to bumper traffic. I could care less what anyone thinks of Auto in the Z. I love the car, it's 100% badA** yeah stick is cool but the car is what makes everyone drool not the shifter. The Auto is quick as hell. I really dont see a difference. Both Auto and stick are great! If your lucky enough to own this car you'll be happy either way!

UPDATE : UPDATE: I had a temporary lapse of reason thinking I could be satisfied with a 5AT sports car. just moved to LA and never experiened crazy traffic like this, not even fron my hometown NYC. The 5AT made sense? Huh? So After a week with the car and a 2 hour drive up the pacific coast highway I decieded I needed a 6MT. I cant explain the craving other than saying my heart was aching for it. So today I did it. I traded in my one week old 2004 Black Touring 5AT and bought a 2004 Silver Track!. I lost a load of cash but gained a ****** F@#$#$ Demon. I am happy now!
5AT was a lot of fun. The car was beautiful but I enjoy the control and power from a 6MT. now that I have driven both cars I can say the 6MT driving experience is radically different from the 5AT. If you dont care about the sports car driving aspect The car offers as a 6MT then the auto is a great ride. Fast crisp smooth acceleration. No shifting and the same outside.
as for my new TRACK. For those who drive it know The 6MT is just a monster. Enough said!