This is the dyno chart from my 1993 Nissan 300ZX Twin Turbo as purchased (I call it "version 1.1" because it was slightly modified at the time.) The output at the wheels was 267 ft-lbs of torque and 249 horsepower. This is the most power I've ever seen from a stock Z.
Remember, HP measured at the wheels includes inefficiency of the driveline from the flywheel on back. The usual rule-of-thumb is that a front-wheel-drive car looses 15-16% in the driveline, a rear-wheel-drive car looses 17-18%, and an all-wheel-drive car looses 19-20%. All that assumes the motor is in the front of the car.
(1999 purchase date, until 2001) To the stock car, add
Engine HP: 300 (factory claim)
As-measured HP: 248.7
(...so if you divide measured HP by 0.82 or 0.83 you get about 300, confirming the rule-of-thumb if you assume my 8 year old (at the time) car performed as the factory intended.)
(2001 to 2005) To v1.1, add
Engine HP: 400 (estimated, but widely tested and documented in other Zs)
As-measured HP: not yet measured
(2005 to present) To v2.0 add
The car is now fully adjustable for camber, caster, and toe within very large ranges. I can set the camber very aggressively on track days and put it back to the mild tire-saving street settings afterward. The ride and handling are both much improved!
As an added benefit, I'm now running R-compound tires on the street. Tire life will be short (6-10,000 miles) but the grip is unbelievable! I'm nervous about driving in the rain though...
(2010...still to be installed) To v3.0 add
Who knows?! For horsepower, I already have...
...which don't help by themselves and wouldn't really be necessary, except that the stock 370cc/min injectors got clogged and needed replacement anyway.