the oem downpipe has one already so you shouldnt need it, I have a jetex on mine with abf downpipe + cat bypass, not had any issues so far. cetainly wouldnt hurt to fit another one though

maybe the hangers you have just cant cope with the extra weight, VW sell rubbers with chains in, I have one on the front-most hanger. I pinched it off a random audi in the scrappy, but the part number if you need it is:
893 253 147 D - zaust rubber with chain - £ 5.09