I am guessing 25% is lost in an AWD after the exhaust is fixed.
2-5% is added for auto tranny's
FWD: 10-15% loss;
RWD: 10-18% loss;
AWD: 17-25% loss.
FWD car around 16-17% loss (Flywheel, Clutch, Gearbox, Driveshafts, Wheels)
RWD car around 23% loss (Flywheel, Clutch, Gearbox, Propshaft, Diff, Driveshafts, Wheels)
4WD car around 27%-30% loss (Flywheel, Clutch, Gearbox, Front Diff, Front driveshafts, Propshaft, Rear diff, Rear driveshafts, Wheels)
From Weistec Engineering:
"For a long time, Dynojet has been the industry standard in measuring power at the wheels. Certain patterns became apparent with the Dynojet dynos which led to the common 15% (2WD) and 25% (AWD) drivetrain loss rules. These rules are usually applied to manual transmission vehicles as automatic transmission vehicles are prone to more losses because of torque converters and more complex internal components. The rules, however, are not absolute or 100% accurate. Transmission type, wheel and tire size, driveshaft weight, brake rotors, etc. all influence the drivetrain losses."
What I didn't see mentioned is that a torque converter will double torque.....................more power loss in an auto tranny, but doubling torque at the line? Seems that need to be accounted for when comparing standard to manual transmissions and power output at the wheels.