I'd like to see a video of what you are doing to get it to do a flat spin from a DEAD stop. Trust me I've tried. It won't break traction at all even with slipping the clutch from 0mph. Slipping the clutch just means it slowly accelerates in 1st gear until it hits 40mph and then all of a sudden the outside rear tire will start spinning faster and cause the car to rotate. That is not a dead spin.No, I mean from a standing start. Try it, it is possible.
I don't think I'm doing anything especially different. I can do standstill donuts with the URD GTE all day long, it's very easy. Just rev to redline in 1st, and side step the clutch. Trying the exact same thing in the s397 911 = revs drop to nothing and tires don't spin.