exhaust goes as follows... stock manofolds left pipe runs into bottom of right manofold, that runs back single, to a y pipe and straight pipes outt he back, whole exhaust is 2 or 2 1/4 cant remmber, i plan on adding some long 4 inch tips prob 14-18 inches long, as it will have flame throwers on it,
the exhaust thats on it for 'period correct' is correct
Correction: BECOMING popular. And by said time guys were squeezing every bit of power they could from flatheads and realizing a slightly larger pipe diameter would make slightly more power.