Upgrading to 3/8 fuel line

Unless he's building a 600+hp monster, that is overkill. The size alone is enough to discourage me, 1/2 is much more difficult to work with, and I used to fiddle with HVAC service, back in the day. I still have my 3/8, 1/2, and 5/8 benders, and may have a 3/4 somewhere