Ignition Kill Switch - ACTUALLY to the ignition

[septavus]

I'm looking to implement a basic ignition kill switch. Having searched the forums, and it seems most people tap the fuel pump, and use that as a kill switch point. However if I wanted to actual cut the ignition, not the fuel pump, as I don't want the engine to run even for a few secs lean on fuel, what's the best place to tap.

My application is full stripped down race car. I just am not a pro at wiring and I'm struggling to follow the wiring diagrams in ISTA and NewTis. I think I've found the relay, but I was hoping someone could just point me to the wire I need to tap.

Or is this not a thing in this car, and I have to kill power to DME or something?

Thoughts?