Beluga I have never run compressed so I doubt my PSI is lower than stock. I'm a 12 gram sort of guy and I only run the red spring because I don't have to even turn the TPC in to get 280fps unless its a cold day. I personally don't like turning the TPC too much that's all.
I'd have to say that the smoothest pumpstroke comes from a Punisher's Customs UC kit. Alas they are near impossible to find now. I have a Rainman, Wevo, Punisher, Duskslide, Phuzzard, two custom built pumps and the Pun and Phuzzard rule, hands down.
Falcon's right, Dropout will get you mad 12 gram efficiency! Matching bore really helped my shot count too. I shoot ultra Evil so I just barely underbore.