I know that in 1979 they (Pontiac) produced a limited run of 6.6 litre trans ams with a factory turbo charger strapped on.
I saw one on the gold coast around 1987.
I never got a ride in the one i saw when i was 9 yrs old, cause i was a complete stranger, but just seeing one brand new and hearing that 6.6 litre motor fire up was something not easily forgotten.