I bought one of Robb's dual mode regulators way back in the early 2000's.
I ran it a couple years in dead-head mode in my other car before switching to injected alcohol.
Well it sat in the box for years until I bought my Daytona and so I put it in this car. I decided to use it in return mode (plunger swap).

https://www.robbmcperformance.com/products/regulator_dm.html

Good to know he is still in business, I may buy a new diaphragm to have on the shelf for the future.