The results arent much different if you put a steed speed comp manifold on a street truck. You lose spool because its not sized correctly for the application.
I had excellent "spool" on my daily driver. T6 comp steed and T6 1.0 83/74 s472. I could of easily towed with that setup. The piece that tied my whole combo together tho was the DPC 4disc converter.
It was overkill for the street but it worked well.
With the passage setup in the Steed manifolds I don't think it's hardly fair to call them a log manifold, they are very well designed.
As for the tubular header in theory not spooling as well because of considerably higher internal volume. . .I've heard that argument quite a bit on header threads. If you really think about it that is a nonfactor. With the exhaust gas volume exiting the engine even at idle and zero boost the volume difference between the two manifold styles is made up for in milliseconds. The difference is miniscule compared to the charge air side of the system since you have a lot of volume between the turbo and intake because of the distance and the CAC.
Steed manifolds have a rather large volume aswell the most of all manifolds on the market. Im guessing if someone actuall cc a steed and header they wouldnt be much different. If anyone wants to do some actual dyno testing with a header verses a standard steed manifold and a steed comp manifold i would build two headers with different size runners to test.
