Before I joined this gun club we call the Marine Corps I built four engines for the same car. One thing odd was that the 425hp on an engine dyno lost 32hp on its way to the rear tires. The prior motor (I only engine dynoed the last two) went 343hp out and 312 at the wheels installed. Calling around I found that a percentage is a bad way to guage drivetrain loss. Your driveline only sucks away the same ammount of power no matter what- assuming you don't change it too.
Also the rear in the car was a 7.5 as it was lighter and well braced for the use I was intending. The car weighed in at 2650 empty.Weight loss reduces the inertial strain on the drivetrain. Also the turbo didn't "hit" the chassis with all the power at once- a hidden benifit of lag. When NO2 was added to cover the massve ammount of lag my final hairdryer had, it was rigged with a .2 sec delay to allow the gears to mesh in the driveline(radioshack has the relay for about two bucks to do this).
This was a '93 four banger by the way that went way to far for street use. It never saw slicks as it was built to corner not break parts. Now I'm trying to mutate a '00 3.8L without taking it through all that mess. I'll retain the 7.5 once more and if it breaks I have two 8.8's to replace it with. Now will some one explain this damn toner ring thing for me. I'd really like to get ready for some import trashing!