Hi Russ,
Sorry, that is suppose to be inside tire.
Regardless of the racing dynamics the welded diff has some issues in a turn no matter what the speed. What I am referring to is the problem that a welded differential has - if the car is turning left the inside tire, the left one, has to travel a short distance. The outside tire, the right one, has to travel a greater distance. They are both on the same axle and since it is welded they must turn at the same rate. The inside tire has to slip to accomidate this and I don't know if it will with a goodly amount of weight on the rear and wide sticky tires.
All I know is pushing a welded diff car around is REALLY hard and it makes awful noises as the tires slip. One can't help to think "this can't be good for the rear end...."
Of the welded diffs in place in SCCA IT racing I know of a few guys who break axles and other bits precisely because of this problem. Some rear ends can take it, others can not. We've got a welded diff in the Jensen and a LSD and welded for the Z car but both of these have pretty good rear ends. My guess is that a Audi 016 would not like a welded differential.
My business partner, Jeff Young, runs a TR8 in SCCA IT, 3.5L Rover V8, is yours the same? He'd be interested in hearing about this PowerTrax thing, I've never heard of it but it seems intersting.
Ron