I remember back in the late 80s, early 90s, the Connecticut State Police had some Mustangs as well as Buick Grand Nationals. I can't remember if the GNs were turbocharged or not, but I do remember hearing that they had the "chip" that allowed them to go up to 140 mph.
Sounds like back in the day,GM`s sales motto was"If you got the money honey,WE got the time". Good luck.Have fun.Be safe. Leo