Were the exhaust headers designed to accomodate the heater boxes or were they designed as close to equal length headers and then covered with the heating sheetmetal?

Also, has anyone ever made a set of equal length pulse headers, with all of the six primaries pipes entering one collector?

Or how about this configuration.
A set of headers for each bank, equal length and equal pulse. Like a Ford GT 40 MK IV.

Thanks very much.

 

the early headers are in fact equal length headers, the heater shrouds were then fit to the headers

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