p0420 02 gtp

i bought it from member awhile back and i have probably put 20k on the downpipe. he "said" it only had like 5k on it when i bought it.

so do you just totally not believe that your inefficient cat could be causing the p0420 code, and the smell of unburnt gas?

No, im just trying to look at all the possibilities of anything else causing the problem. thanks for all of u guys input.