Velocity stack, for 2" HS8 SU carb .
With all the talk about how to spend more money on performance it only seems natural that perhaps optimizing what you have is the basic first step. The addition of a "stub stack" within your filter is one of the cheapest ways to improve performance. The principle is that the more air you get into the chamber, the denser the charge, the greater the chances of increased horsepower! These stub stacks are designed to do the job and easily fit into most filters.