I am new to this site as far as being registered but I have been reading posts for a while now. My audi has gave me that code and only that code (135 k miles) and I know it is for the passenger catalytic converter. I changed the spark plugs and have tested the coilpack as well as the pre cat sensors (through a DIY I found on here). I was going to try to switch the post cat sensors from from one side to another to see if it was a sensor problem or not (another idea I got from here) but I quickly found out those are very hard to get to. My question is this, is it a must that I change my catalytic converter (meaning will the car only cause me additional problems) and if so, what is the best/cheapest option ( in California). I dont mind putting something on it that will not pass smog since I know some people that will pass it for me (I know I know ,people these days, lol) but what I am most concerned with is my car not giving me additional problems and having to pay a big amount of money later on, which I dont have. All answers are appreciated, Thanks in advance.

P.S I dont sense any major failure on the car, expect that sometimes, when idle and in Drive it jerks a bit or somewhat seems like it looses a bit of power, but never to the point where it seems it will turn off, not close to that.