[EricH]

You think you're OK because of R71 and R77: Keep reading. R90 specifically says that the outputs of multiple solenoids can't be plumbed together.

I do suggest paying attention to the flow restriction on solenoids, or lack thereof, which may allow better air flow.

You could also use shorter cylinders, and run two in line with each other as a replacement for each cylinder you're currently using, each with its own solenoid.