i need to know what size fuel line to run and can the standard steel lines be used with a skyline tank or will i need bigger lines

i9 bought 6.5 mm line (1/4) today and im not sure if its big enough ,and can i just run rubber lines all the way or run steel 1/4 inch lines under the car ? and can the standard line be used or is it too small ?

EFI uses 5/16th of an inch as a standard.

I'd run same for feed and return to a surge tank. The feed to external Bosch EFI pumps is half inch. Most of the fuel can be satisfied by return line and 5/16th from tank to surge tank. Anything over 100kW at the wheels and the standard 1/4 inch fuel tank line will give up. But it will get you through rego/engineer at 10psi boost..

Some people go up a size in EFI fuel lines.. Except of worked V8s and 400+kW monsters, I don't see the need to run 1/2 inch fuel lines.

You can't run EFI rubber hose the length of your car. I remember it being quite expensive, and you can't use copper or aluminium tube.