OK - yes, I think Greg's got the key point in that the WUR seems to not function as a true regulator, only a ratio regulator.

As for legality - might as well discuss it here. Last I heard, fuel-injected cars are allowed to use adjustable fuel pressure regulators. GCR ITCS section D.1.a.6: "Adjustable fuel pressure regulators are permitted."

Greg (and any other rules nerds monitoring): are you aware of or can you find any rules that might contradict this?

PS - there is a way to make the stock one adjustable, though perhaps not the most convenient while installed!