FRH manifold bolt size

[vtecds1]

Does anyone know what size bolts go into the holes circled red? I forgot all about them and I already installed the runner and spacer. I tried m8x1.25 which was too big and m6 was too small.

 

[TylerAdamson]

Pretty sure those are nitrous bungs which should be a pipe thread. Maybe try 1/8npt or 1/16npt.

Edit: Might want to check these out.