I believe that car was avilible with a turbo option that could be further tweaked. Some of them are pretty quick.
I knew a guy who had a Grand National. Don’t remember if it was the GNX, but it might have been. He was the worst driver I ever knew. He flipped it right over. He said something broke in the suspension, but I knew better.
Buick Century’s were NEVER fast.
86-87 Buick Regals with Turbos were fast.
Century’s were ALWAYS something 70 year olds bought.