Performance Motorsport I think to date has run a 8.19 ET(not sure). Another 350Z is running in the same time area. The power output is somewhere in the area of 1600-1700HP.
There's also 3 (I know of)Pro modified 350Z's running VH45DE engines.
I don't think these qualify under the topic heading, "boosted 350Z's", so I won't even go there.
There all having the same problem as nissan 350ztt says, "Traction".
Goodyear has been working on tires, both street and slicks that well hookup and correct this problem. When this happens watch out, you'll see some 7's runs for the VQ35DE engine cars.