It was close, maybe a drivers race with a slight edge to the WRX.
Stock 287/274 350Z's have run low 14's for most, and high 13's for a few. A great deal of the advantage in the quarter mile is the launch of AWD. Watch this video:
YouTube - stock 350z vs subari sti
I think a stage 2 WRX is pretty close to a stock STI, which is why I linked the above video. I know I was hanging with stock STI's when my WRX was stage 2. Frummadig the AWD obviously has an advantage. In real world driving, such as being in traffic and needing to move out - the 350Z was faster than my WRX with the Cobb stage 2 map.
I loved my 350Z for how it came stock. A lot of fun to drive, easy to learn the balance and handling, but lived on the knock limiter from the factory. With a ton of bolt ons they wouldn't make more than an extra 50whp. Forced Induction is the way to go with them, but then you need to replace the internals. I never could justify the price vs risk of modding my 350Z. So it was stock. ROCK EFFING SOLID though. Never had a problem with it. Got myself in and out of MANY nasty situations. The car handled very well. Would buy one again later, but my eyes turned towards a better Z.