Compressor > pressure valve > 4cylinder > Pneumatics
will result in MUCH faster cylinder deployment. The regulator is a big restrictor to airflow.
We store our air in 4 Clippard tanks connected directly to 2 SMC valves, that are in turn connected directly to our piston. We designed it such that there is no tubing between the storage tanks and the cylinder, only high pressure fittings. The air flow we get with this arrangement is many times what we achieved by storing air at high pressure then feeding it through the regulator.
The downside is that we have no high pressure storage, only low pressure. This lengthens our shot-to-shot time. We added a pressure sensor so our shooter knows when there is enough air for a hurdle. (We have a second method of hurdling, so this doesn't slow us down much.)
Here is a shot of the height we get with this arrangement:
