2V Exhaust Manifold to FFR Catylytic Converters

[ATOLightning]

I plan to use 4.6 2v Exhaust Manifolds on my 3v (with 3v flange or adapter of course) along with the FFR 4.6 Cats. I know there is a difference between PI and NPI manifolds. I believe the driver side is 0.5" smaller on the PI version. I may be wrong though.

So my question is: Which manifolds bolt-up to the cats best? The older 96-98 or the newer 99-04 manifolds?

Thanks,
Michael