what size fuel line for nitrous setup?

go with a minimum of a 140gph pump.
1) run -10 from cell to filter
2) run -10 from filter to pump
3) run -10 braided or 1/2" aluminum hard line from pump to a Y-block or fuel log of some kind that you can mount fuel regulators to
4) fuel regulator with 2 -6 lines to carb
5) fuel regulator with 1 -6 line to Im guessing a plate NOS kit, and leave the other outlet of that regulator available for flowing you fuel pressure for the NOS kit.

doing this will give you room for growing.
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