[Schwag]

gotta disagree with darkangel about cutting rubbers.
The hop up sleeve's length is nearly irrelevant as long as it's not cut too close to the nub that descends(like so close it will pull into the barrel) The only thing that is affected is the extra padding and tension it provides between the IB and hop up unit.
Obviously if it fills the whole tube it will provide better stability but even that isn't much of a difference if the barrel and cut sleeve are tight.
There have been times when I have had to cut sleeves to fit guns and times where it was so tight that using a shortened sleeve was the only way to push it all the way in without warping the outer ring.
This may not apply to all applications but I've cut many a rubber with zero issues.

and maybe I'm thinking about a different barrel but all the madbull tightbores I've seen have thinner walls and a smaller diameter with thicker hop-up sleeves to compensate.

how are you guys liking the ultimate hop-up?