Breather from the two tanks is going to the top one.

Bottom one is main line to engine.

Of the other two inlets does it matter which is the inlet from the pre pump and the inlet from the return line?

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But he's thriving and striving and hugging the turns.

I would put the pre pump at the top, so that if any air makes its way into the prepump, it is further away from the outlet to the pressure pump.....