I like the BFG Silvertowns, but I read a long thread on
www.performanceyears.com and all of the Pontiac guys on there swore by the Diamondbacks. One complaint they had about the SIlvertowns was that the stripe on the BFG's was more maroon than bright red. I've mostly seen the Silvertowns on non-red cars, so I didn't have an issue.
I still think 215/65/15 is the perfect size for early Z's, and I think they look better on 15x6's than they do on 7's.