I had a classmate back in high school that got a 1973 Gran Torino Sport with the 351 4 barrel Cleveland. He had a lot of money and had his engine "built" , put I think 12.5 to 1 compression pistons, the biggest hydraulic cam that was available back then. He had headers and sidepipes put on it. He left the transmission stock and had 3.00 gears in the 9" rear end. Then his high school sweetie got knocked up and she was driving this as a daily driver. Mind you- this was right when they did away with Premium gas, right around 1975. She pulled into the small town gas station, where we were standing in the open bay door. She filled up with regular, we yelled at her to get on it when she left. It was the most horrific detonation I had ever heard. Like large marbles getting thrown in a big coffee can. Yeow!