On a dynojetthrough what method? a coast test? ISS and OSS monitoring combined with the road speed and numbers from the dyno?
The most significant losses in a driveline are generally in the diff. you won't be changing that by swapping to a manual.
if you want a manual transmission to have one, then by all means do it, but I think that you'd find drivetrain losses aren't that much greater with an automatic, and you lose the advantage of torque multiplication.
There is no way to know what the driveline losses are without first knowing what the motor makes at the crank. They will be different for each car, absolutely unique to that specific set of gears/transmission, even down to wheels and tires. For that matter even down to WHAT dyno the car was strapped to. They're not all equal. Was it a mustang or a dynojet?
Dynos measure whp and not bhp so they must've made some assumptions and calculations to guesstimate bhp.did they random guess the 252BHP then?