In answer to the OP: Not a lantern archon's chance in Nessus would I allow it, and I'd give them three options. Either everybody forgets they just said that and in future they involve the GM in the game, I pack up my notes and let them tell each other the rest of the adventure (since they don't need me), or we step back in time and resolve this idea.
"Alright, so...where did you get the bombs? You made them? Ah. Give me some Demolitions rolls, then. We'll get to the concealing, planting, wiring, and detonating them later, provided you don't blow any rolls. I'm going to be nice and say you've been working on these during down time...no? Alright, you've been bomb-making in the jeep. Take a penalty."
The GM is there to translate player actions into world outcomes via the rules, and vice-versa; if he's removed from the loop, it's just the players narrating and he might as well go home.
On Janx's sub-topic, Cyberpunk 2020 included an Awareness/Notice skill. And with those combat rules, it was your life-or-death skill a lot of times.