What Jannetty sells is a shield, but its not a box. It just seperates the filter from the turbo. You dont have to cut anything to install it. Do you need it?, no, but it helps. You can get a K&N wet but where it is located it wont be a problem. If you are going to be in a real dusty area, you should consider a 25-0880 pre filter to help keep the filter clean, they are only about 20 bucks.
Exhaust blankets are nice too, they will help control underhood heat. Persoanlly, i dont like to insulate cast iron with anything since it leads to more rusting and cracking.