You need to run an overboard fitting of sufficient size (-12 min) to dump the excess fuel http://free.***boat.net/ubb/wink.gif . Just kidding. All it means is that the pump is capable of flowing a certain GPH at a certain pressure. if your engine uses more than 70 GPH, the pump will lose pressure. I'd go with the Holley 130 GPH pump and run a regulator. Cheap insurance since the price difference isn't outrageous and it gives you an excuse to build more power later.