I've had this since having my last clutch installed over a year ago, kinda like the whole car shudders and makes a groaning sound while slipping at a certain point on the clutch, or literally a knock knock knock knock sound really fast. Hard to describe - maybe I should take a video. Didn't have this problem with the 7223 HD that I had previously, if memory serves this one's a SO with one of the parts from the Evo clutch and the other from the Magna one.
Put it this way, unless you have over 200kw atw, stick with the HD if you plan on it feeling nice to drive lol