'70 Grand Prix 400 with headers, 2.25" exhaust with an H pipe and long glasspacks, Rhoads lifters, open air cleaner, etc. In a world of Chevy small blocks, the Pontiac engine had a unique sound.
I always loved the sound of a Mopar big block, too. My only Mopar was a slant-six, though. It sounded like a sewing machine.