Just wondering if anyone has installed one of these, and actually used the failsafe part?

I see a bunch of threads of people installing them. But, how did everyone hook it up regarding the failsafe? Do they cut ignition? If so how? Did they bleed off boost? If so, how? etc.

Ordered everything for my car to get it back on the road for next year. And would like to install one of these, just looking for any advise.