Although I'm not able to presently play, it has been my experience that no more pressure is required than a seal between the lips and mouthpiece. Having played multiple brass from picc to Suzy, this I learned to adapt to. Yes, I know others have used more ... and those are the ones I believe are encountering all the problems and now ask what to do to correct them. For my formative years I had a 3/8" overbite and an upper right incisor that was diagonally broken (latter crowned, but gone completely now, except for it's root). Yes, even then I had impressions inside my upper lip from that broken tooth that I lived with and adapted. What I never noticed was a mpc impression on either of my outer lip surfaces even after the longest gig I ever played, a PA Governor's ball, both 3rd trumpet and 2nd trombone.