I have a vw that I just purchased used. It also had very bad swirls, I used XMT #4 with a little pressure using the PC. I would say 95% came out but I still have a little work to do. I then followed with XMT #3, XMT 360 and finally Collinte 845. Sorry to not answer directly but XMT #4 seemed to work pretty good on my car.
If memory serves, 83 DACP measures around a six in abrasiveness. Thus XMT 3 is probably quite similar and 4 a little more abrasive. The XMT's dont dust as much which is a real plus.
XMT 4 is some pretty heavy duty stuff! I would probs try a couple passes with a 6" yellow cutting pad. If that doesn't take it out then I might switch to Menzerna, or maybe Optimum Hyper Compound.