I've been thinking about installing a low pressure switch that will light a dash indicator when the fuel pressure gets too low (because of clogged filters).
The Fuel density Compensator has an internal regulator set at 20 psi, so anything below that will cause the FDC to richen the mixture.
With that in mind; I'll put a 20 to 25 psi switch after the final filter, there's a boss there, just drill and tap.
While researching this I couldn't find a decent fuel system diagram. I'm sure there's one in some TM, but I gave up looking!
So... I made my own, see attached: