Kit does not require all this but i wanted to run a 6" velocity stack for many reasons. First of all my favorite part about this kit is that the turbo is pointed right at the passenger headlight, anortest distance for efficiency/protect against heat soak, straightest tubing possible to maximize efficiency, biggest piping possible(3.5")coldest way possible(sucking air right behind headlight). The aluminum velocity stack should make the turbo sound even louder when it starts gulping up air.