Rick1-10,
I doubt that you can get such a pipi off the shelf. So the most practical approach would be to make one yourself.
If I were in your situation (and I may actually be in the near future) I'd buy a 3" pipe and some flange material, then remove the cat and 'copy' it in a simple, thru pipe. Should cost under $70.
However, if your purpose is gaining a few HPs then I think you should talk to RT or read the info on their web site. You may end up gaining very little or, theoretically, even loosing a few horses.
If you end up up with this cat-replacement pipe, could you please post the bottom line results (net gain/loss).
Jay
