That truck bed liner spray stuff won't do squat! I have tried several brands in my trooper helmet and it is just a rubbery stuff that won't do any type of reinforcing from what I can see. I ended up fiber glassing the helmet inside in the end.
FYI, there is no such thing as fiberglass reinforcement spray. It is a fibeglass cloth that it is layed into the helmet and a special resin for the fiber glass cloth is applied on top of it and it then hardens into the durable fiberglass shell. It can be gotten at any auto store, hard ware, or big store like Walmart and K-mart.
Lynn