Stem, poppet, whatever you want to call it

. The stock arrangement on the QB relies on a raised, v-shaped ridge in the valve that the resilient seal on the head seats against. Seems like a recipe for turbulence, and air flow restriction. The design I'm using is conical, and seems to make power, but I'm not sure it's the best choice. Just to be clear, here's a pic of mine:

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The step at the rear is just the spring seat. This SEEMS like it should flow well, and yes, the seat has been re-contoured to match the valve head, but I've long since found that lots of things related to air guns are counter-intuitive

. So I'm just wondering if there are other designs that might work better.
And I think I've asked this before, but is this plain nylon the best material choice? I also have Nylatron, Delrin, and even some Teflon on hand, I used this because that seemed to be what everyone else was using

. If it matters, I'm strictly running this on air (well, nitrogen, actually), with no intention of ever using CO2. And to reiterate, my goal is max power, so if a different material might make a difference, I'm all ears. Later.
Dave