I'm working on a check valve for my T8/9 that is similar to this. I've got pictures somewhere. However, I'm not doing it to get more shots per 12 gram out of the gun, I'm doing it so that I can run back bottle air without replacing the magazine nipple with the dummy nipple. This would allow you to shoot until your back bottle is empty, vent what pressure may be left in it, then pierce a 12 gram and get 18ish more emergency shots.
But to answer your question, yes, it should work in the T8.1, the regulator is identical from what I know.
__________________ Anonymous Assassins Paintball TeamJust look for the pink shirts MCB Feedback SpecOps Feedback Laws of Thermodynamics; 1) You cannot win, you can only break even. 2) You cannot break even.