Hey guys,
the port size doesn't matter too too much i don't think, i have 1/4" npt ports on my bags, but with 1/2" line and 1/2" valves, it lifts in about a second and drops even faster, with mufflers on the dumps. I just got a 1/2" npt to 1/4" npt reducer fitting, and the orifice was almost exactly the same as just putting the 1/2" fitting straight in. Before i upgraded it all to 1/2" i had everything at 1/4"... with manual valves, talk about slow! I have some videos of my car with 1/2" line and 1/4" ports if you want to see, let's see if it works...
wheel
1/2" line
Don't mind the slowing down on the lifts, it's because i only have 4 gallons of air stored, hopefully more soon! Good luck! hope the info helps.
~Frank~