So I have a set of tangerine racing fuel lines installed. Should I route the fuel in the engine compartment so that that it flows from one carb to the other, then to a pressure regulator, then return fuel to tank?. It looks like originally the fuel lines dead end at each Weber.

If using a pressure regulator, install it before connection(s) to carbs. If there is only a single inlet to each carb, use a brass 'T' on the output from the regulator and a hose to each carb.

Personally, I don't like using pressure regulators if I can help it. We just removed a high pressure (FI) pump and installed a new 3.5psi pump, a 'T' and blocked off the return line to the tank.

I've got a similar setup to Mark's although with AN-6 braided lines, alloy tee and PMO fuel bars. Just got rid of the troublesome Holley regulator which my mechanic says is unnecessary anyway on my car (track use). We chatted about putting in a return line and may do it someday, but I've done without one for like 9 years now.

Thanks guys, I don't know why I had it in my head to do a return line.

I still think a return line is desirable/beneficial, but numerous cars seem to do just fine without one...your choice

A return line is good for power (at least theoretically)
lots of ways to route this:

Thanks Brant, that's really cool. Looks like the rectangle is pump, circle filter, hex/triangle pressure reg? I was thinking option e, but maybe D

you got the symbols right
I can't take credit for the drawing
I've run 3-4 different ways

it also depends if you are carbed or fuel injection
you don't want high pressure pushing against a carb needle and seat really
(although with the right pump you won't have that high pressure really)

with carbs, you want to keep cool fuel flowing past them at all times
more power...

so I like option B and use it on my race car
brant