Definitely the sickest car I've seen in this forum. I run a DPI platinum track and have push. But, my chassis guy and I agree that it's very unlikely caused by the diff, the T2-R isn't much different so I'd look elsewhere. You probably have the push in high speed corners as well but you're just not driving it fast enough to notice the push in the high speed turns. Aero also hides mechanical grip issues in high speed turns.
My car has had chronic push for many years, over the last year I've worked with a very capable chassis setup guy who happens to be a multiple national champion auto-xer. We've dramatically reduced the push by adjusting the following:
Adjustable front sway bar
Adjusted the front roll center
The car is still not perfect but it's about 3 seconds a lap quicker at Thunderhill than it was before I started working with my chassis guy.
NASA AIX Outlaw West Coast