Not sure I understand what "bottom air box" means, but the only stock unmodified air/filter assembly I am aware of that is not legal is the LS SS one, regardless of what body the engine is updated/backdated into.

My definition has always been that if the cross section flow area that lets the air into the "duct" is larger than the cross section area of the TB and any bypasses to the TB then you have the makings for increasing pressure...so don't do that.