As much as I love my Z i'd trade it for a stock supra if I could. The Supra is legendary, especially given the aftermarket available. BPU's easily make 450 whp. A single turbo swap on low boost and pump gas makes close to 600 whp with supporting mods. It's a one of a kind car. Now, if I had the $$ i'd probably still go for the GTR (similar 6 cyl twin turbo from factory) but the supra's are considerably cheaper. You can find them with built motors and single turbo set-ups on Ebay for $50k. Stock GTR is still 80-ish. However, once you start really bumping the power above 500 the Awd of the GTR will make up for the large initial price difference allowing you to put that power to the ground.
http://cgi.ebay.com/ebaymotors/1994-...ht_2747wt_1168
This one is a bit much, but makes 550 whp on pump gas and is a gem. The guy is looking for $50k
There's others on there in mid 20's with BPU upgrades.
EDIT: OMG there's one on there with 31k miles!!! Only thing is you need to order a single turbo kit for it. The guy took the stock twins out and never finished his project. What a steal though for that car.