How much parasitic loss with M6.

What is the magic % for the amount of parasitic loss on a 1995 M6 with 4.10 10 bolt rear-end.
I am guessing around 15%.

Is this right or am I off?
Thanks

Based on actual measurements on my car, first on the engine dyno (Superflow), then on the chassis dyno (Dynojet) in the same shop that built the engine:

NA: at 500 flywheel HP losses were 12.6%
1-stage N2O: at 635 flywheel HP, losses were 12.3%
2-stage N2O: at 765 flywheel HP, losses were 12.1%

The balance of the system was a steel flywheel Street Twin, totally stock T56, 3" chrome moly DS, Strange 12-bolt with 3.73's, 17x9.5" wheels with 275/40-17's.

I'd say to assume closer to 13% with "stockish" HP.

On a M6 with a STOCK setup the Loss on a dyno is between 16/18%. Note the Word Stock.;)

Well we have anywhere from 13-18%

By stock do you mean stock M6 and 10 bolt rear end.

So when you are no longer stock, why does the number seem to change

Whatever it came from the factory with is stock.

I thought loss would be greater through a 12-bolt???

I would expect the losses to be greater with a heavy Street Twin, a heavy 3" chrome moly driveshaft (19#) and possibly a bit higher with the 12-bolt. Not sure why using the lighter weight stock components would increase drivetrain losses by up to 5%. Maybe someone could explain.