When pressure is bypassing the needle and seats it will cause also eratic pressure. should be using Viton (spelling?) needle and seats. 100's of race cars use the blue holley without a return with no problems. on a street car though I would rec it to keep the pump cooler and keeping the pressure from spiking. Also check your regulator make sure its working by adjusting the pressure up and down. By the way thanks for the xpipe worked out great.