I run a 3.91 Quaiffe at the short tracks (NHMS & LRP) and a 3.64 for longer tracks (WGI & M-O). Need lower yet for Pocono, possible to the stock 3.15. I am running 225/50-16 tires. The 4.11 is certainly too much for any track.

My crew chief changes the diff in 20 minutes at the track, just pull the half shafts and drive shaft and drop it out. Since no suspension points are moved there is no need for a realignment. Hope that helps your planning.