Yeah,, its safe. Im running a similar setup exhaust wise . When you install it just make sure the screw is wound all the way out that should give your 10psi
I bought one a few weeks ago and he still had a fair few left then.. Just checked ebay and he has none listed. You might want to PM simark87, he's the guy that makes them.
Your best bet is to use a contact adhesive.. you dont need special carpet or vinyl... just apply the adhesive with a brush so that you get a thin coating on both surfaces ... let it go touch dry... then carefully place the carpet or vinyl on to the surface... be careful of air bubbles if doing vinyl.