I did a quick search and never found my answer...
I am using a used rb road race header with eveything else brand new, my question is do I need that ACV block off? If I do I can just make one, my 7 is an s4 and the header has the back pressure pickup tube, do I need anymore block off plates? What size are the nuts/bolts/studs that I will need? I plan on having the dual always thru so no cats but I will be using the backup tube with the aux ports still functioning

 

bump

 

you block off the acv...

the answer is in the rb product page for the header:
http://racingbeat.com/resultset.asp?PartNumber=16127

you can make the blockoff plate, it's easy, just get some plate steel or aluminum and a coping saw to make the tight bends easy, or a hack saw if you don't want to follow the shape tightly... and a drill to make the holes.

you could also just fill the ports with jb weld or weld them shut if you have that capability.