Your grenade or rocket has to land/hit the door for the manager to trigger.

~10 seconds faster than any other strategy.

This is how you should do this mission if you want to get the armor or just don't want to do the riskier strat of shooting a rocket at the manager's door (and it is risky because I've either died or almost died multiple times when attempting it). The roll at the end is a new addition.

(Compared to really good SMG execution)

1. Rocket shot at the door to the manager's room saves ~10 seconds.
2. Rocket shot at either of the pillars, killing/knocking down everyone so you can climb, saves ~1 second.
3. Doing #2 with a primed grenade (starting the prime just before entering the restaurant) is no faster, and will almost always result in you losing more health.