Obviously, different combos will yield different results.
I know someone with a pretty good running sb mopar in FAST that tested stock manifolds vs extrude honed ones back to back on the chassis dyno.
With his combo, it was basically worth nothing.
I've found this myself.
If the manifold is at its limit power wise, most anything won't help it.
A bunch of circle track guys were doing it back in the mid 90's. Never found anything on the dyno or track with those particular manifolds, which were some GM junk.
