Going through the fuel system after upgrading the pump and wanted to add an aeromotive fuel pressure regulator to ensure that the higher pressure from the pump is mated with an equally higher performance FPR.
After looking underneath in the fuel filter area, figured out that the FPR needs to go in the area behind the inner fender liner.
To do this upgrade, you need to replace your existing fuel filter/fuel pressure regulator, with just a fuel filter. I used one from a E34 540, exactly the right length and no FPR.
Ideally you want the FPR as close to the fuel rail as possible. in this case it's about 2 feet from the fuel rail, so that's not so bad. The crowded engine bays of the E39 V8's (540 and M5) make it difficult to find any room!
After getting the FPR and 6AN fittings, you need some braided SS hose (tried to do SS hard line and I do not have the patience...). One for the supply from the fuel filter (about 12"), 1 about 32-34" long for the return line, and 1 about 24-28" long for the supply to the fuel rail. You can make your own or have them made... One thing with braided line, is to secure it so it does not move against anything that could abraid the line. The car vibrates and driving will move things around so you want to make sure it's all nice and tight! 3 - 6AN to mail hosebarb fittings and your all set. Another option is to locate a fuel pressure gauge in the engine bay with a moroso 6AN male to male adapter with a 1/8" NPT tap for a gauge... This is what I"m doing. For this you need a 3/8" hose barb to female 6AN
Aeromotive FPR-6AN fittings
12" braided line
32-34" braided line
24-28" braided line all with 6AN female fittings
Moroso 6AN-6AN Male adapter for fuel pressure guage
1 female 6AN to 3/8 hose barb
2 male 6AN to 3/8 hose barb
See some of the pics below for mounting location...