1. Install a pipe plug like this in the collector
http://www.newmantools.com/petp/143_2.htm
2. Make a plate to bolt the header flange to.
3. Drill and tap a hole in the plate to install one of these
http://www.timsautosupply.com/shop/d...lugs-14-in-npt
Or one that matches your air hose.
4. DO NOT USE LINE PRESSURE. 10 psi is more than enough. Typical pressure inside a header in use is very rarely over 3 psi in extreme cases.
Whatever you do, DO NOT stand in the way of the rubber plug and do yourself a favor and point it towards the ground.
We are not trying to make a potato gun here, if you know what I mean.