[vex]

Now, I'm aware that you can modify the fuel rails to support -AN and run parallel.

I just happened to pick up some NPT taps (1/8", 1/4", 3/8", 1/2", 1/2"). Now I could never make heads or tails of peoples information with regard to the fuel rails of an S4 being just tapped. (I'd read they needed to be welded, and when I'd attempt to confirm it I'd get different people saying that you can just NPT tap it)

My question is, with the sizes I have for the NPT taps will I be able to modify the S4 fuel rail to support the -an lines using an NPT to -AN line adapter?

I'm planning on doing both the Primary and Secondary rails by tapping (as opposed to welding). Will I be able to use the sizes I have (the two 1/2" taps are for different hole sizes: 13/32" (18mm) and 45/64") or will I have to buy a larger/smaller tap?