Naca duct, I use them on my splitter but can be mounted anywhere really. 

If going in your bonnet I suggest using at minimum ASA but you will want something that is temperature and UV resistant. 

If they are going under your splitter if its near the sump I would stick with ASA but otherwise it doesn't need to be UV resistant so you may be able to get away with PETG as you will need it to be somewhat impact resistant