The pics say it all. Look at the pic where he's in the tube for 30mins. He only has real fluid retention at the base because that is where the most extreme pressure and suction is. But for cut guys their base foreskin length is still tighter and shorter thus exposing the tight cells to more fluid retention. Uncut guys have clumped skin, therefore the cells are not as exposed. They are only exposed LOOSELY. The inner penis expansion is a lot better accommodated because of this, whereas cut guys will develop fluid retention at a faster rate than they would EXPAND their inner tissue because of the tight restriction. A cut guy will not only develop fluid retention faster at the base because of these reasons but also the next site would be the sensitive and thinner skin under the glans area. Within 30 minutes I would have fluid retention packing these sites completely. So the conclusion is for uncut guys it's more inner expansion and less fluid retention. For cut guys it's the other way around. Both can gain but the difference is quite apparent who will get quicker more real gains.
The extra skin is more protective and provides a better spacious FIT for the penis inner tissue expansion. These are the reasons why uncut guys will have much greater true expansion rate.
Remember the uncut English Youtube guy that tested the [words=https://officialhydromaxpump.com/?uid=6&oid=2&affid=98 ]bathmate[/words] over the course of several weeks? It's the same result at Castiel