[ReefBlueCoupe]

Mine does this - feels to me like the ELSD and TC as others have said. There's really nothing else it could be. It's an instantaneous back-and-forth of the rear that lasts for 1/2-1 second at WOT or hard acceleration while the car is already moving. It sorts itself out after that.

Keep in mind we are dealing with GM-level refinement and calibration of a complicated system trying to manage 650 ft-lbs, not Italian-supercar-level refinement and calibration. Either the calibration was rushed, the engineers didn't encounter this scenario during development (unlikely), or the processing of I/O from/to the ELSD unit/TC system just isn't happening fast enough (processing is too slow). It'd be great if there were an updated calibration to take care of this, but I haven't heard of anything. Then again, if it's not the calibration but is instead the processing speed that's the problem, nothing but swapping ECU components will fix that.

It's never felt out of control to me, but was unnerving the first few times I went WOT from a roll and didn't expect it.

I've felt mechanical diffs do this on the dragstrip in the past, but usually it's WAY more pronounced and doesn't go away, and with big drag tires and big sidewalls, things can get out of control quickly. Hence why we have spools and Waveloc/similar for high-hp cars accelerating hard.