I forgot to state on that M.W. motor all testing was done with headers The first set was a set of hooker 1 7/8 primary pipes with a 3.5 inch collector for the A bodies, the dyno operator made a set of dyno BB Mopar wedge headers that where 2 1/4 primarys, 25 inches long into a 4 inch collectors, I thought they would hurt the motor down low, they picked up the average by around 17 HP and 20 ft. lbs (tested from 3000 to 6500 RPM) All the gains where above 3500 RPM