I find that the lip pressure is determined by what sound i want to make, for raspy yelps is looser, for cuts and kee kees the lip are tighter, and almost pinched off behind the mouthpiece, regardless the diameter of the opening. Lost the lip stop off my favorite trumpet a few years ago, havent found it to be hinderance, also use two very different diameter mouthpiece wingbones, same approach, different tone . Years back fella killed a bearded hen in Kansas, told me if i made him a wingbone i could have the other set, this will raise eyebrows but i dont even carry the hen wingbone. Had more success with the others.