I beleive it has the outlet for the return line, but I simply plugged it as my car did not have a return line. It worked flawlessly on my Bird and I was pushing 405hp at the rear wheels. My friend Mike who has a built 455 in his 65 Tempest did the exact same thing and it works great.

Prior to using the SD fuel pump my Bird used to run out of fuel at the top of 2nd & 3rd gear. Once I installed the SD pump, NO problems at all. I think just having the larger bowl/resevoir solves the "running out of fuel" issue. At least it did for me and my friend Mike...