Custom built Air Filter Block Off I have seen many different cars with block offs to the air filter. When I first put in the K&N Filtercharger, it was under the impression that it would be pulling in quite a bit more air than the stock air box, but some of that air would be hot air off of the engine. So, the concept here is to obstruct the flow of air off of the engine. The piece will be more effective once a front mounted intercooler is installed. This will allow air to flow through the front fascia up into where the stock side mounted intercooler previously sat, and up into the area around the air filter. At this point it is a true cold air intake system. I started with a cardboard box. I picked one that some things had been shipped to me in, and carved it until it fit over the air filter in the shape I was looking for. I left the bottom, left hand side, and front completely open. The top panel goes all the way to the left hand side of the engine bay, but the front does not touch the headlights. This will allow for air coming in under the hood to get caught by the block off. Once I had the cardboard template fashioned, I had my neighbor Chad finish it off. Chad works as an installation manager in Circuit City's Roadshop, so he has had a lot of experience with custom design work. We used a sheet of aluminum flashing (used by carpenters installing or repairing the roof on a house) to wrap around the cardboard, giving it a polished metalic look. The flashing was used because it was thin and easily bendable. A thicker piece made out of sheet metal might have been preferable, but I did not have access to the material or the tools required to bend/shape it. Also, the flashing did not require any welding. The only possible change to the design I am considering, is the incorporation of insulation of some sort. If the block off gets too hot, it is just going to warm up air as it is pushed into the air filter, transfering the heat. Below are pictures of the air block off, as well as links to the web sites of other people who have done similar constructions. See custom air block offs made by: Shawn Gradek (Currently none of his pictures seem to be working.)