True, the gaskets can be a little forgiving if the manifold mating surfaces aren't square.
I think the problem you could have, is if your old manifolds have been remachined at some point.
A remachined intake with a fresh new exhaust may be difficult to fit as a set since they fit in two places... against the head in one vertical plane, and to each other in a horizontal plane.
If you tightened the bolts to the head first, you may have a gap in the horizontal. When you torque those bolts, you would then be putting stress on the castings. This could eventually cause a failure... like a cracked manifold.
From this, I can see why it might be preferred to replace both parts.
I liked the "tickling" term. It means to me, that you tighten gradually, the vertical plane and the horizontal plane similar to the bolts on a head... in a type of sequence. Then at least, you'd be averaging the unsquare error to both planes.
You'd still have stress on the castings though.
If it were in my budget and to insure I had no problems, I reckon I'd replace both parts with new.
Just thoughts...
Jerry
