[Vwdiesel] Turbo Diesel Exhaust Brake?

[Tyler "Casioqv" Backman]

I do a lot of heavy duty towing (5000-11000 pounds) with my Volvo 760TD
(VW 2.4l turbo diesel engine) and have been considering designing an
exhaust brake system to allow for stopping larger loads, and increasing
the life of the brakes (even without a load). Many companies (such as
Jacobs and Banks) sell exhaust brake systems for big pickups with
Cummins and International motors that consist of a butterfly valve with
a orifice in the exhaust after the turbo, which causes high exhaust
backpressure (but regulated by the orifice) to help aid in engine
braking when descending down a long grade with a heavy load. Does anyone
know if this backpressure might cause any problems with the engine (such
as blowing valve seals or turbo seals?) What if I were to install the
butterfly valve (a throttle body from a gasoline engine) in the intake
after the turbo to create a vaccum exhaust brake? I know I would
probably have to also get a blow off valve for the turbo before the
butterfly valve, so I don't get a backpressure shockwave when the valve
closes. Do you think the vaccum would pull oil past the rings or valve
seals? Also, does anyone know if perhaps VW installed a factory exhaust
brake on these engines at some time? I know they were used in some
pretty heavy duty vehicles such as the Pinzgauer (factory rated to tow
11,000 lbs) and large delivery vehicles.

-Tyler