Just thought I'd show a relatively stock Supra Dyno Slip. Being a sequential twin turbo, and using a small primary turbo the performance isn't too bad, but yes, there is a big jump when #2 comes online.
I happen to have a '94 Supra, and it is a real hoot to drive. But on the road courses or autocross courses it can get to be some fun when #2 kicks in and you aren't expecting it.
I know you're talking about the TDI, but I saw the mention of the Supra motor and thought I'd pass on some info.
As a european i see the v10's every day on the road here, and a few of the members in my club have them as roadcars, so I know the engine and the history of it.
That said, i would reccomend you NOT to use that engine if you want to have a car you can trust to take out in the backcountry. If you want it as a "poser" then the engine is fine.
If you want something with power, take a new Toyota 6cyl 24v diesel from one of the newer VX100 you can pull 300-340 HP out of that and still have a engine that is more reliable and a more usable torque range than the VW v10 ever will.
There is a reason VW took the 5cyl engine and NOT the v10 when they build this years Paris-Dakar rally car. The V10 is just not good enough if you want to go offroad on other then the local golf course.
Now that I have say "you can't" you proberly want it even more