Though I did moderate port and bowl work my Ed Heads Exhausts port @ flange are the stock 1.30" x 1.80" . My Primary Header tubes are 1.50" x 1.95". I've always heard it is "best" to leave a step but I've never even heard of anyone doing the alternatives such as radiusing the Ex-port face, making a funnel or perhaps matching the full depth of Ex-port to the primary tubes bore.....
With so much emphasis on Intake port flow it seems little attention is ever paid to the Ex-port & Primary Header Tube interface as a combination. Throwing a wrench in the mix, my headers are standard issue Mustang shock tower impaired with the primary tubes starting out of their flanges with a radius vs the "by-the-book" straight shot out of the port. In the least since the primary flow is forced into a tight radius, a step there may not be all that logical.
