I will have to agree it does not look like plumbing for NOS. If it were a direct inject NOS system it should have a Y nozel and a second set of lines for fuel. Is it possible it was Alky injected with just air doors mounted on top?
I have NO idea what it was plumbed for however I have put spray on a LOT of cars and never seen it done hat way. I will have to call :surrender: on this one!