Rugging at the Phaeton V8 at 1500-1800 rpm

Hello. Who of you can help me. I drive Phaeton V8 and had it converted to gas. I had problems before, however, in the mentioned speed range of 1500-1800 revolutions the vehicle and that in every gear, with a sensible driving mode and not under load. What can this be? According to VW you have carried out compression measurements and the 2nd and 3 cylinder have a pressure of 10 bar and the rest has a pressure of 12-13 bar. If the problem is here or comes from the transmission. The microphones have already been tapped and noises have been detected in the transmission, however, according to VW this transmits from the engine to the transmission. I hope there are some specialists here who can help me with my problem. I have to be satisfied with it all the time. MfG Marc