I recently received the replacement gas ram in my Crosman NPSS and installed it. On the invoice, it's described as "Nitro Piston, revision b," which means that somewhere along the way, there was the original and revision a versions. The nitro piston that originally came with my gun was losing power having only put ~1000 rounds through it. So I called up my contact there and he told me to send him my defective one and he'll send me a replacement. I told him I did not want to send him my gun because I got it grouping real good at 65 yards and I was afraid they'd just swap the entire gun on me. I also have brass breach spacers in it vs. the plastic ones (that were never installed in my rifle). So, I got the new nitro piston in and put the rifle back together again. I put 4 shots through it and I can feel the power. I need to put it through the chrony and see what speeds I am getting with 14.3 grain pellets.
While at the airgun shop, I happened to test fire the new Trail NP, and the shop pro told me it was shooting 800 fps. I didn't put it through the chrony, but if my NPSS with the new nitro piston is giving me 800 fps, I'll be very very happy.