JesseT

No they don't. They are of a rising pressure type, not rising rate. They keep the fuel pressure constant across the injector, so when manifold pressure goes up/down the fuel pressure follows to flow constant amount of fuel in unit time. The rate of rising of the pressure is 1to1 (fuel to air pressure) and is constant. A rising rate regulator has a rate that varies with manifold pressure; the fuel pressure goes up more than manifold pressure. I've never seen or heard of a car that originally had one when it rolled out of production as new.
Rising rate regulators are sometomes used to compensate when standard ecu or injectors are retained after fitting an aftermarket turbo. A really cheapo trick that won't carry far.