dual exhaust options for my 351m build

im building a 351m to a 400 as most due.

im looking at doing dual exhaust for it. i want long tube headers, but should i run 3 inch from the collector all the way back or keep it at 2.5. i dont want to loose alot of the back pressure. or is there not that much of a difference from 2.5 to 3?

It is more of a funtion of RPM. The higher you rev it up, the more you need the bigger pipe. If you are making a mild street engine, the 2.50 diameter is going to work just fine.

JOE SHERMAN RACING ENGINES