I followed some simple instructions that SS gave me and made one of these devices. The parts can all be purchases from Lowe's and this should most definitely be done prior to any tuning.

Here is SS's thread that outlines all the parts. I happened to have that Samco hose laying in my garage so I used that.
Anyone have some good info on pressure testing? - IWSTI.com




Pleae note in this pic I was just test fitting and you wouldn't want to fill the intate system with 20psi without a clamp holding the tester in place