AN6 PTFE hose with a stainless steel braid, sold by the foot. This is the size most performance fuel systems are built around, covering feed and return on EFI setups as well as power steering and smaller oil cooler circuits. The PTFE liner does not permeate fuel vapour, so the fuel smell that plagues rubber-lined project cars simply does not occur, and it stands up to ethanol and methanol blends that dry out and crack ordinary hose. The stainless braid guards against abrasion and holds the hose dimensionally stable under pressure. Use only AN6 hose ends made for PTFE hose, and respect the minimum bend radius when routing.