Opinions differ and will continue to differ on the effects the outer contours of a mouthpiece have on its performance. The PeakTone® model features an Outer Shape control which allows you to change the outer form of your mouthpiece, using the two controls, Overall Length and Outer Style .
Overall Length does what it says on the tin and allows you to change the overall length of the mouthpiece, adding a length of tubing between the cup and the stem. Such changes do not affect either the cup or the fit of the mouthpiece in its receiver but making the mouthpiece shorter will make the mouthpiece/trumpet combination sharper will increasing the length will flatten the resulting combination. In order to accommodate the length changes, the geometry of the backbore is also changed.