I've got a GT and I'm leaving mine the stock box for now. For some more noise, I did remove the "baffle" or tube that helps muffle sound.

You turn this:


Into this:


This is what gets cut out.


It may help air flow a little bit since the air gets spread more evenly over the filter. If you ever changed a filter on it before, you'll notice a darker circle right in the middle of the filter.