On an s5 with the stock FPR at the aft end of the fuel rail, when installing an aftermarket FPR do you simply remove the vacuum line and move it to the aftermarket one? Or do you have to replace the rail (I don't remember if it is removable or not)?

I'm running the Walbro 255, with an s4 primary (banjo barb fitting in place of the FPD), and s5 secondary. Too much fuel at idle!

 

you have to remove the old FPR from the rail.,Run the fuel line to the FPR and use the old vacuum line to the NEW FPR.

 

you'll need a s4 rail and remove the stock fpr from it, put on fitting for a fuel line to your new fpr and hook up vacuum stock vac line. Or cut off fpr off your s5 rail and have a fitting welded to it.

 

this is kinda what I figured... it looks like the s4 TII ones are impossible to find. Are the N/A and TII ones interchangeable in this case?

 

The s5 FPR is welded/crimped to the rail...

 

I saw walbro and s4 when I typed.
You can use a S4 TII secondary rail but watch the spacing on the injectors.you may have to use washers in between the rail and upper manifold so the injectors aren't squished to the grommets.
look at RisingRpm fuel rails and it will say 4mm spacers come with the kit.I used the rails on an s5 but I didn't need the spacers.I ran ID injectors.

 

n/a secondary rails will not fit a TII block. the primary rail also has the inlet and outlet on the opposite sides.

best bet is rising RPM rail sets, rather cheap and work well as well as look good.
http://www.risingrpm.com/products/pr...rail_kit_a.asp

only thing i do not like about them is the fasters, they should use a smaller head hex bolt or allen bolts. can't get a socket between the bolt and rail without a super thinwall socket.