BAC's interchangeable? NA to turbo and S4 to S5?
 

Just like the title states I'm trying to see if bac's can be swapped from na's to turbos and s4's to s5's and vice versa on both accounts. Please list what parts do swap over and which don't(lines and such) thanks

FC BACs function the same, but there are physical differences. TII BACs have the idle adjust screw (except the weird S5 J-specs), while NAs don't. S5 plugs are oval & S4 plugs are rectangular. And of course, the inlet piece will face different ways on S4 NAs, S5 NAs and TIIs.

Would the idle adjust screw on the TII BAC cause problems with the NA idle adjust screw on the throttle bodies?

You can adjust the inlet for the BAC but you need the special screw driver tip (it looks like an asterisk, I forgot what it's called). Once you undo the tiny screw, you can rotate the inlet. It takes some minor "persuasion".

You could close it all the way and it would be like the screw isn't even there.

torx, or tork, or torck,howerver its freakin spelled