upgrading the fuel system

So I am working on upgrading my fuel supply. I was planning on simply installing an adapter from the stock fuel supply line to 3/8 NPT then into a "Y" dist. block. From there two -6 lines into the fuel rails. Doing this mostly for looks however I have seen some folks run a new -8 line from the pump into a regulator, then onto the rails with returns at the opposite rail end back to the regulator and back to the tank. I am not so sure I understand the purpose or need for the return lines. I am running a mild cam, ported heads and spray. I dont think I have any current supply issues but since I am spending the $$ now, I thought I would try to get a better understanding of the need for a regulator and return lines.

Any one get into this before?

No idea, but curious also