Carlos from Spain:
GT:

 Correct.. This is a traction issue combined with the brake steer. NO LSD was criminal...

They can massage it with stiffer springs and different electronics but the transmission is the issue in my opinion (and first hand experience with the car). 

I remember you mentioned concern about the rear diff issue long ago when the specs were coming out, what was the reason for doing away with the mechanical diff? did they ever mention it?

If I had to venture a guess, a rear LSD, a less intrusive electronic setting, less variable electronic shocks, and overall stiffer setup with more direct steering reaction, would radicaly change the car... oh, and also sportier much more agressive sound as well, they may not see it as something that would improve performance, but its important towards the overall impression and experience.

 Yes i did, many many times with many different people from the development program. I was told that it interfered with the brake steer, those 2 were not working together well.. But the other main reason was the 30kgs that it would weigh. I think at the end it was decision on marketing motives. Those 30kgs would make the mp4 lighter than any other car in its class. The brake steer that the mp4 has is x10 more intense than the one found on the 997.2tt. Their choice is now backfiring i fear.