The primary runners don't have to be very long because the exhaust pulses are split between the two header parts, just as long as they arrive at the final collector individually.
In reply to # 1594743 by mtnwings Hi, The 4-2-1 headers I found on ebay just came in, great price but no collector from 2 to 1. My question is this: The ports are round not oblong like most all headers I have seen, 1 3/8 inch diameter. Also they are shorter than ones I see on line, only 13 inches from head to collector. Any idea what these are? I can match the ports, no problem but should they be longer for better performance? Also, the collector from 4 to 2 ends up just 1 1/4 diameter , shouldn't that be larger? I believe the four pipes from the head are 1/1/4 wont that cause a lot of back pressure? I can cut the collector up 1/2 an inch and weld on larger diameter 2 into 1 pipes to the exhaust system, any thoughts?
'S all for now