I have read the threads on this but there doesn’t seem to be a consensus on which one is best. Which one have people had luck with? My mechanic is recommending the API
There is no consensus. Some people swear by anything with flex joints. I have seen/heard about those cracking just as frequently as ones with out. Many quality aftermarket ones crack as well. My personal theory is the newer style split manifold design does the most to prevent this. You don't hear about those cracking that much. I have been through 5 different manifolds/headers until I converted to the later style design and haven't had an issue yet knock on wood. Could also be that the Doug Thorley headers I have are just really good.
@SkylinesSuck same problem, just took off a cracked manifold, inox with flex joints.
What's your replacement? I'm looking for the best in term of longevity can you post a pic of yours or link?
And also just got reference, factory twin manifolds are matched to the 0331 head which has smaller, higher ports. I wouldn't install newer style dual factory manifolds on an older head meant for older manifolds. It'll partially block them off. Most aftermarket headers feature larger ports though and can accommodate both head designs.
And also just got reference, factory twin manifolds are matched to the 0331 head which has smaller, higher ports. I wouldn't install newer style dual factory manifolds on an older head meant for older manifolds. It'll partially block them off. Most aftermarket headers feature larger ports though and can accommodate both head designs.
I attempted to do this a few years ago without having all my ducks in a row - obviously I wasn't successful. I remember there being a difference in the head ports but couldn't recall exactly what that was. Thanks for the trip down memory lane.