Since this is in the Touring forum, I'm assuming you have an R3T.
I have the D&Ds and they are direct replacements for the stock pipes, one on each side. The cats are in the muffler housings on the R3T so either the TORS or the D&Ds will eliminate the cats.
I just bought a full Jardine system, it was delivered today. Nothing wrong with the D&Ds, I just want to see if I can wring a bit more power out her.