I spent a lot of time early in my career when airbags behind headliner canopies were being developed and implemented as side rail air curtains. We worked a lot with with a company called Autoliv (owners of Morton Thiokol - the company that made the solid rocket boosters for the space shuttle) timing out explosion of the propellant to escaping out from under the headliner within milliseconds to inflate quick enough to protect cabin occupants once the sensors detected a collision.
Slow motion film footage was our best friend in determining where headliners needed to "break" to allow the curtain to drop. The first time I saw the films I was amazed at the violence of the explosion,,,,,,and understood the power it took to put a space shuttle in orbit. Really cool stuff.