yes its a direct bolt on yes it hooks to the stock feed line but it is not a side flow rail......i will break it down like this........with an 03 rail setup the fuel is entering thru the pass. side and exiting thru the drivers side....the pump is gonna keep pumping thru the pass. side and reg after the rail backs the fuel up.....so what that does it pretty much keeps a constant flow and pressure all the way accross the rail.....when to enter the fuel from the middle of the rail and then with the reg mounted in the same spot the fuel enters in the middle then gets backed up on the drivers side......so essentially under high boost with lots of fuel flow how is the reg gonna back the fuel all the way thru the rail and back to those 2 injectors before the inlet......its like electricity.....it will take the path of least resistance......i had a cnter feed rail setup and swapping to a side feed ttally changed my afr's on the same day in the same conditions.....and the knock gauge went down 1 or 2 after.......
this is what i had to hack to get a proper returnline setup done to this rail
