Hey guys, dropping in a 525 where a 496 sat. The 525 is plumbed for 1/2" ID hose and the boat has 3/8" ID. Do I need to change out supply line to 1/2 all the way to the tank?

If you only do part of it you are wasting your time. I would change it all plus the fitting in the tank. The fitting in the tank will be the real restriction.

Does anyone have a part # for a fuel shut off valve that does not choke down from 1/2"? My Earls shut off #6 in to #6 out valve workings are not 1/2" straight thru!