CAREFUL: I live where Random Technology is headquartered (Atlanta) and bought a set of their bullet cats. My dealer tech put them in. I have been told by local muffler shops that Random does not actually manufacture anything. What Random sold me were something like "CATCO" cats, which are often used on ricer cars. I now have one cat that has no substrate whatsever. Gotta think the other will go soon because they cannot handle the flow/exhaust temps of the Viper engine.
Perhaps the ones that many tuners here sell (whichare RT models) have more ability to handle the flows/temps, but the ones RT sold me were worthless. That said, I just passed GA emissions with my cats in their present state.
Make sure that you are installing the RT model that other are using sucessfully !