Bob, Thanks for your reply. I have had my share of other aftermarket manifolds which "almost fit" and leak around the welds which is why I was interested in the iron manifolds. However, your comment is bad news to me in the sense that I was counting on headers to be the main performance enhancement on my mild 350 build up based on the dyno data of several succesive improvements of a Goodwrench 350. Now I wonder what headers they used; I was only interested in the diameter of the tubing as 1 5/8" but maybe they used longer headers. So what you are saying is that the shorty headers do not give as much performance improvement as longer tubes? If that is so then maybe the ram-type headers are just as good and the only thing of interest is the ease of fit in a narrow frame.

Don Shillady
Retired Scientist/teen rodder