The most likely variants of the Regal that you'll find in a classified ad, especially among American car enthusiast circles, are the ones with the famous turbochargers: T-Type Regals and Grand National (both are 2-door coupes, and you can spot them by the bulge on their hoods). The 1985 Buick T-Type Regal came with a Garret Turbocharger good for 200hp and 300 ft/lbs of torque, stock. Grand Nationals only came in black, so if you found it in any other color, it has been repainted.

 

With a little bit of modifications, you can have yourself a muscle car ready for the drag strip. It is believed that most Regals were sold with 3.8L V6 SFI engines. The G-Body style has changed very little from about 1978 to about 1988 (when the new bodies came out and the Regals stopped being "muscle cars" and became more sedate front-wheel drive family cars, up until 1997). In the 80's, GM produced identical cars under different brand names with little differentiation:

 

The 1978-1988 Regal and Grand National belongs to the "G-Body" class, which includes the Pontiac Grand Prix, Oldsmobile Cutlass, and Chevrolet Monte Carlo. If power is what you then power is what you'll get. In typical big-displacement American fashion, this engine gave you power when you asked for it. No problem there. People got weaned on this nice 6-cylinder. You can only imagine what the turbocharger in the T-Type/Grand National will do! The shifter is on the steering column, which is good so you have nice bench seating in the front.