[Brian R.]

I'm sure that vacuum hoses, many of them being associated with emissions control systems, have specifications which control their properties, including the material of construction. If the manufacturer of the hoses has not certified that they are in compliance with the California Code of Regulations requirements (probably an SAE specification), then they are probably not legal. If you search CCR, you will probably find that any modifications to the emissions control systems with uncertified components is not allowed.