It's worth noting that the factory re-inforced these pieces for a reason.
In a front end/head on crash, the drivers and passengers lower bodies including their legs are thrown forward by the forces.
These panels were re-inforced to keep them from breaking thru the thin plastic and being damaged by the sharp bits of the steering column on the drivers side and the heater/climate control components on the passengers side.
That said, I have put the 89 underdash in my vr-4, but I left the glovebox lid as delivered.
I'm okay with taking chances for myself, but I dont want to think about a passenger being injured.