Just to answer your question Gary, factory wiring for the fuel pump isn't up to the job.
Cable gauge is to small to carry the desired amperage, causing volt drop (which gets worse the longer the distance) , which in turn means that down the fuel pump end of things its only getting ~12V instead of the ~14V it needs to run at FULL capacty.
This setup would use a relay switched by the original pump wiring, of which there will be a diagram somewhere in here.
ps. get it tuned