Primary size and length on SC engine

Header size for max perf on a S/C motor does not matter, as long as there is no restriction. You will need to know your exhaust port square inch measurement and your tubes (inside diameter square inches) should be no smaller than the port measurement. Also 3 1/2" collectors should be OK. The collector (I.D.square inches) should be no smaller than 4X the inside of the primaries.