and in my Phoenix, it did nothing to the firewall.
Dustin employed multiple layers of protection from the engine forward to the fuel cell: a shaped fiberglass plate that mounts close to the engine, a 3" gap to the false firewall (thin piece of steel), and about an inch later, the firewall itself.
I'm sure it depends upon the direction and force at which the shrapnel is ejected, but in my case everything launched forward was contained by the fiberglass plate. Because afterwards, when we got it into the pits for inspection, we found impact marks only on the fiberglass plate - the false firewall was unscathed.
Hope that helps (although something tells me you would figure it out - you have skills I can't even fathom).
John