Hello Nikola
Most ET2 Users use the ET2 supplied pump, it makes very little noise cannot be heard from 6 feet away and is placed on the floor next to the turntable.
When you order a car you have options. You can select a bigger engine, you can select more horsepower from the same engine. Bruce offers this bigger engine as the 2.5. And he can modify the horsepower the smaller and larger engine make based on your needs. From approximately 3 PSI stock ET2 (base product) to 19 PSI. This applies to the ET2 and the ET2.5 which is the bigger engine with the bigger manifold. Every ET 2 or 2.5 was made for a certain amount of PSI in Bruce’ lab.
Public Chat Forums attract Aficionados in every hobby. Some of us here, represent the extreme end. Many of the discussions are about these mods and upgrades we have done. There are many modifications and upgrades that can be done and this is all possible because the design has few limits. I trust you and others have enjoyed these discussions.
Why Wittgenstein ? I would prefer Newton as what we are discussing here is basic physics. Think of your childhood teeter totter and trying to enjoy with a friend that was not the same weight as you. Do you remember the teeter totter and having to sit closer or further away from your friend in order to balance? The concept is the same here. The PSI gives us lift off, and we can fly sideways and pivot with no friction unlike other air bearing designs.
Does Slivovitz boost memory Nikola ? I can tell you that Scotch and Canadian Beer does not.