How much of that is on purpose (to sound cool) vs necessary (to provide 400hp) ?
They have a massive big block engine, but new cars are also big (5.0L = 300CI)
How much relates to emissions issues in 1974 ?
Catalytic converter reduces carbon monoxide, but makes airflow slower.
So, older cars has less restriction, which means you can have more air/gas mixture combust and faster exhaust flow ?
And how do annoying modern day “Honda ricer” exhaust mods relate to all this ?