I doubt mouthpiece popping has any relevanceâ€¦well, to anything. http://www.grmouthpieces.com/questions4.htm You can believe whatever you want, if thinking the moon is made of cheese will help change your sound and your playing for the better, more power to ya. I wouldnâ€™t worry about where the tuning slide is, either. Just put it where it needs to be. I see Michael Sachs play his Bb trumpet every 4 or 5 days. His tuning slide is pulled out pretty far, maybe Â¾ of an inch, maybe as much 7/8. I donâ€™t know exactly, I havenâ€™t cared to bring a ruler with me and measure yet. Heh. Anyway it is out much farther than mine. Guess who sounds/plays better? Not me.