What are you shooting?
I tried to shoot one with my Notos and it just broke open. No explosion.
Going to try with my 25 cal L2 next.
I think the notos just doesn't put out enough energy to make it explode.
I'm shooting a modified AV Avenger 22cal. It is shooting H&N Baracuda 21.14gr pellets at about 875FPS, so it is about 36FPE. It is hitting pretty hard.
The Baracuda are more "pointy" than traditional Diabolo, so this may make a small difference as there would be more force applied to a smaller area when it first hits.
It looks like the Notos caps at about 20FPE. Here is a chart:
Picture Credit -
https://www.outdoorlife.com/gear/umarex-notos-review/ I think that the energy that you are applying to the target makes more difference than the velocity by itself. You can blow them up with arrows, so those would be heavy, would be going slow, and would thereby deliver significant FPE to the target. I don't know how hard it would be to get the power up on that gun (adding plenum, increasing hammer spring, reducing valve spring, boring out the valve, increasing the size of the transfer port, etc, etc, etc.)
Your Leshiy 2 should be more suitable to make these pop with the 25cal putting out 35-40FPE which is right where I am.
Good luck, and don't forget to record your success so you can share it with the rest of us "kids" that like to make things go BOOM!