Ports, ports, ports, let's play with ports! I got my Condor a year ago and it had the newer .28" stem valve with a top hat or port called a "ring-loc", that adjusts with two little crescent wrenches, not the older kind with the tiny allen grub screw. It came with a seemingly large orifice, and other sizes are available:
Take More Control of Your Air Usage and Power Levels Our Ring-Loc™ Valve Pin Kits allow shooters to have more adjustability from a new Condor or CondorSS
www.airforceairguns.com
I haven't played with those yet as I'm on CO2 in my backyard with that gun. I need an actual range to let that gun really fly.
I don't know about the valve spring as I haven't disassembled a valve (yet). I understand the newer Talons and Escapes may have a similar type of valve but a smaller orifice as their target power level is a little less.
I have a CO2 adaptor that has the older grub-screw port with a .25 valve stem, and the port itself is huge. The CO2 adaptor port with the grub screw does not play with the ring-loc kit orifices.
Older valves such as that may be able to play with Talontunes' "Quick-change top hat":
Quick Change Top Hat - AirForce Accessories
talontunes.com
as it looks to be .25", but that is out of stock so I haven't tried it yet.
Cheers,
Mike