I need all you nitrous guys...

Even with the smaller sniper system, you'll only get about 6 14 sec. sprays. Do you see gobs of black smoke when he hits the button? You never mentioned when the bottle was last filled. One last thing, NOS blows head gaskets to the point where all seems OK until the cylinder pressure increases and then you've got problems. Get a nitrous pressure gauge, the ambient temp could just be too cold.