fuel pressure regulator
 

okay first question,,,are aftermarket fuel pressure regulators adjustable or what? I saw the parallel fuel mod and i got to wondering how the fpr knows how much fuel to let through. Or does it even do that? Does it limit the amound of fuel let through? gah im confuzzled. can you use the stock fuel rails for the parallel fuel mod?

Yes, most aftermarket FPR's are adjustable. Most people are still using the stock fuel rails, you just need to adapt fittings onto them to suit whatever hoses you're using.