I have driven open, quaife , and welded. The welded is faster into the turns, under brakes. It wont lock up the inside front wheel, the midturn -out is much faster(10-20 ft most turns)> it is the hardest to drive. My car goes straight, in the turn, off power. It needs full power and puts it down the best. the fastest in the rain, by far. Same engine, (a year older) @ sebring , the car went from a 2:48 to a 2:45. That is from a top ten car to a winner. The setup required a lot less rear bar and less rear air#. It was scary loose withthe open diff setup. I thought that I had made a big mistake the first lap, but luckily I had a easil;y removed rear bar, .
The other side benny is that the car keeps going when driven hard over the curbs, often needed to make the pass or open the exit line, like tower turn or T 14-15-16.
I wil take the locker, regardless of price, it is the fastest for me and is vastly more entertaining than any semi locker.
I have a quaife in the rental car, but when it is for me to go fast, it will get the welded.)that trans is for sale)
Mike Ogren