I have the quaife, and have a best of 14.1 @ 98. The car was not running strong that day. On the street, the tires break lose at about 5500-6000 rpms. I dont think this hurts the performance too much since it is not just instant tire smoke, but the tires just chirp with a very subtle wheel hop. I think that is just the quaife transferring the power between the wheels. I would think an open diff would spin worse at the top of first gear. I have to shift to second not long after anyways, so I dont think it is hurting much.
One of these days I hope to have the car at the track on a good day. Given my 2.3 60' times, that should net a high 13.
