Go carts run spools in the rear. (I know apples oranges)
I don't think Trevor has ever run auto x, he was too hungover to make the last one of the season this year. I know in my experience there was never too tight of a corner in any of the courses I ran, that I couldn't navigate them with the reduced turning radius of the welded diff, and the big difference was exiting corners, and not just having my inside tire spin and not go anywhere. It actually caused me to have some oversteer issues if I wasn't careful. The 79 was setup like most of the vw rabbits that I competed against with no front sway bar, and iirc I found a big bar out of like a ford ranger and fabbed some brackets to make that work for my rear bar.
That car was down right scary in the rain merging on tight overpass loops, if for some reason I had to get out of the throttle. I had one time in exactly that circumstance, a big piece of plastic blew up out of the inside of the loop, and I just saw it with my peripheral vision panicked as I wasn't sure what it was dropped right out of the throttle, and the car looped about 4 times before it came to a stop, in the right hand lane on the free way. Thank god traffic was light, and people managed to get around me.