If you use Swage-Loc or Parker-Hannifin steel or SS fittings you can get away with compression fittings (but not on my car anyhow) as we had literally hundreds on each gas turbines/LM2500 engines with up to 5000 psig for fuel and hydraulic devices. Unfortunately, the local Auto Zone or Home Depot don't sell them, only the el cheapo brass fittings, made 'somewhere else'.