His manifold is a skunk 2 which is already pretty thin in that area. There is 3 to 4 mm of material between the TB bore and the IACV port. Opening the bore to 68mm would mean removing 2mm of material around the entire bore. While it can be done it’s a little risky for a setup that really wouldn’t require it. If you were to break through on the port the IACV wouldn’t work.
man just boost it and stop worrying about this bullshit 
didn’t make the #'s u were expecting? no prob bob, turn up the boooooooooooost