Fuel lines running the length of the body should really be hard lines for safety reasons. Flexible used only at the connection points as necessary. Not only is it much safer and less prone to a dangerous leak, it is also considerably cheaper to run a 3/8" SS hard line. A high volume/high pressure electric pump as used with an EFI system will empty your tank incredibly quickly if even a small cut occurs to a soft line. All that gas will be spraying all over the underbelly of your car...you know, where that hot exhaust piping resides!