Back in 1977, I was stationed at a Navy school in San Diego and my second favorite movie of that year was Smokey and The Bandit starring Burt Reynolds, Jerry Reed, Sally Field and Jackie Gleason and I saw it at a Drive thru located on Nimitz Avenue (Long gone since) and another big star was the 1977 Pontiac Firebird Trans Am which sold like hot cakes after this movie was shown. With a 400 cubic inch engine, it only had 200 horsepower since in those days due to pollution standards, the car engines were throttled down. Car performance really declined in the 70's.
But this car, the Pontiac version of the Chevy Camaro, had that most distinctive hood art on it. 
My step-father had a friend who had one of those. He claimed that with only a bit of work, he got that almost stock engine up to 380 horsepower. He said a lot of guys did the same thing, that the stuff Pontiac did to reduce the horsepower was easily fixed. Don't know if that's the truth, but seems likely to me.
Back in those days, if you opened the hood and looked into the engine bay, it was a horrifying sight since, due to pollution controls of the time, there were multiple hoses and other garbage to reduce Nitrogen Oxide exhaust levels, Carbon Monoxide levels and particulates and the engine compression went from the average of 10 to 1 in the late sixties to 8 to 1 by the mid-seventies. When I worked at an ESSO station back in 1972, Regular gas was $0.23 a gallon and regular Octane was 90, ESSO Plus was 95 Octane and ESSO Extra was 100 Octane. In 1973 ESSO became EXXON. Cars in those days did not have the electronic controls we have now, so it was all mechanical and it really cut the performance of the cars. The way a lot of people improved the mileage and performance was by removing all that pollution crap like catalytic convertors, recirculating hoses and more. But then by the early 80's, computerized controls came along which allowed engines to get rid of carburetors and put fuel injectors on all cars which dramatically improved mileage and performance and then automatic transmissions gearing was changed a lot. My 1968 Impala had a two-speed power glide transmission. Today, my 2019 Chevy Spark has a six-speed transmission and some like the Suburban come equipped with a 10-speed transmission. So yes, it wasn't difficult to improve performance in those cars since the basic engine was still there, just remove the pollution crap and away you go.
