I got an 08 6.7 with auto trans...(just blew) anyway it has a h&s mini maxx with 5 inch tbe and sinister diesel egr delete. When I hammer down on it I get lights like fuel rail pressure too low and the relief valve popping prematurely. I just did my oil change and got on it yesterday and got low oil pressure now. Another dumb thing that happens is even if I'm driving normal a perform service light will come on and a code won't show up with it the truck will just say perform service??? I'm wondering what you guys think like maybe a weak lift pump or fuel pump ect... I'm not sure I think I want to shim the relief valve anyway but I should probably tell you guys I usually drive with the tuner on performance mode (200hp) do you think the lift pump is fine and maybe it just can't get enough because the motor needs more obviously when it's on performance mode right? Tell me what you guys think about the codes and all!