I'm currently having a custom set of high-flow cats made for my 2002 by a guy here in Albuquerque who is very good with stainless and TIG welding. The biggest hurdle by far is sourcing the right flanges so that the cats will mate correctly with the OEM headers. As a matter of fact, that's still holding up the project and I'm not sure when it'll finally get done.
Anyways, once he's done with mine and we test fit them, making test pipes should be easy for him to do. I was planning on posting a thread about my friend's custom high-flow cats here on Prime once they are finished, and I'll ask to see if he'll do test pipes as well.