u will find on most high $ or serious race cars that u will see what they call a stepped tube header the reason for this is to get the tq of a small tube header and the power of a large tube header.the ones i had built for my old 88 camaro they started off 1 an 7/8 and about 8inches in they changed to a 2 an 1/4 then it went into a 4inche collecter.