M1 SP vs Air Gap

Locomotion said
The dual plane ran best when the deeper side plenum jets were 2 #'s bigger than the shallower side. I accidently stumbled across the idea when I happen to notice that the cylinders/plugs fed by the deeper side plenum 1/2 were colored lighter than the shallower 1/2!

Now that is a compelling thought! Below is a pic of the 340 I have sitting to the side that the stealth came off of. Maybe I am imagining things, but it appears there is more Carbon build up on the middle 2 (lower plenum) cylinders than on the outer 2 (upper plenum). Thoughts on that?