I believe the way from the factory is to run rubber lines straight from the fuel selector to the fuel tanks,,, I’m not comfortable running rubber through a metal wall. There’s the aspect of it rubbing, there’s the aspect of a fire getting through the hole, and the aspect of creating a draft that might be noisy or make the cabin cooler. And none of those seem desirable. Also inside of the cabin I’m using aluminum lines so it never has to be replaced, hopefully. So I connected these hard connections through the wall instead. But I must say that all of these customizations do really increase your build time.