Smog Line

You could remove the air tube that runs to the back of your heads, but you will need to plug the holes in the heads with something like a threaded pipe plug in the right size.

There is a curved "S-shaped" hose coming from the smog pump that runs to a black plastic air diverter valve. There is only 1 inlet on the side that the S-shaped hose connects to, and two other connections (one on the bottom, one on the side opposite the S-shaped hose).

One of those two outlets supplies air to the metal tube that connects to the cylinder heads that you've been asking about. The other outlet (which points down) supplies air to a metal tube that runs down to the catalytic converters.

If you are only capping the thermactor holes in the heads, and not messing with the air being supplied to the converters, than you would only need to plug the outlet on the plastic valve that was feeding the metal tube running to the heads.

There should be a short section of hose that connects the bar to the black plastic air diverter valve. Just pull that short section of hose off and cap the valve.