Been wondering about this myself, as I have a system sitting on the shelf, awaiting install in one of my track cars, so I sent an email to Canton, got back a reply asking me to call one of their apps engineers named Bob.
Bob had some nice suggestions, I told him about the hot oil pressure ranges of our V6 engines and he suggested the
24-273 - ACCUSUMP EPC VALVE 35-40 PSI kit, which opens the accumulator dump valve at 36 to 37 psi. He felt that the high (55 to 60 psi) kit would be cycling open too often, and the low kit (20 to 25 psi) would open to late to protect the engine.
He also offered some great suggestions, and explained the operation of the accumulator valve.
The EPC valve, when opened by the low pressure switch, allows fast dump of the accumulator into the oiling system, but, due to its design, even when closed, allows oil to flow from the engine into the accumulator to keep the accumulator charged, they say it "empties fast but fills slow." This keeps the refilling oil flow from straining the engine oiling system, because the normal (unrestricted) path into the accumulator would offer less resistance than the engine itself, and this might starve the engine during accumulator refill.
He suggested using the toggle switch to control the EPC valve, and that you would leave the EPC valve turned off in the pits and even during a warmup lap to keep the accumulator charged, then close the switch and enable the EPC system when you start to race.
He also suggested wiring a dash light, like a shift light, across the EPC solenoid valve so it will light when the EPC valve opens to dump the accumulator. This will allow you to easily see what sorts of behavior are causing your oil sump and pump to lose pressure; left turns, right turns, always lose pressure in turn three.... He suggested using an incandescent lamp, as LED lamps may have a short life absorbing the inductive kick from the EPC solenoid valve coil.
Bob said he's been writing a tech note and meaning to get it up on the web site, I encouraged him to finish it, as this isn't the first time I've heard this question.