Dyno #'s with Trickflow Heads

My buddy bought a set and wanted to bring them over for some flow testing but I’m a little to busy right now and he’s not going to use them for awhile so no big hurry. Michael Beard also put a set on his 10 second car and he puts on lots of runs so I will follow his progress. Problem there is he is also switching from a 727 to a powerglide.
What people mostly do,make multiple changes at once...but miss out on which was the most impactful.