On my .970 the turbo spools very quickly, there's basically no lag.

If you floor the go pedal without pressing the kickdown switch, does the trans shift from 1-2 or 2-3?

Granted my car is around 700 lbs lighter, but this should give you an idea of the acceleration your car should have: https://www.youtube.com/watch?v=srXc2xV0fO8

Hooking up a temporary boost gauge is a good idea. You could also use a vacuum gage on the the wastegate to see if the computer is successfully commanding it to close.

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.