I'm fairly certain that's not a factory valley pan. IIRC the heads require a valley block off plate - which would'nt need the washers or reinforcements. And yes - it's sealed with silicone.
Going from a street build to a race build, at what point does one have to start to worry about valley pan buldge? 500+ hp? Is it at a certain level of cam lift or duration?
You should never have to worry about the valley pans bulging up. If you do it's because the rings or gaskets are not sealing the combustion pressure. It's not related to oil pressure, horsepower, camshaft, weather, fuel, boost, or anything else. If the head gaskets seal, and the rings seal, the pressure stays where it's supposed to.
