Al, all my old leaf spring cars would respond(go faster and quicker) to more air when I had let them down to low with 3400 Lbs. + plus cars on smaller tires bias ply slicks like 10.5x29x15 when they would shake from wadding up
Those where mid 11 to mid ten second cars
I've never let the tire pressure down low enough on my ladder bar cars or 4 link car to make the tires wad up like Mikes are 5.5 lbs. is not much air pressure