Does anyone know what a "permitted alternate intake manifold"  would consist of?

Thank you-


9.1.5. Production Category Specifications components to effect an annular discharge configuration is prohibited. 6. Air cleaners, velocity stacks, air supply ducts and cold air boxes are unrestricted. 7. Stock or permitted alternate intake manifold(s) can be ported and polished. It/they can be cut apart to facilitate this work. When the manifold is re-welded, the external dimensions of the manifold must remain unchanged from stock.