Comfort is a relative term.
We want you to fit the mouthpiece to be as comfortable as possible while still reducing your snoring. The smallest amount of jaw extension that still reduces your snoring is the best. Start by molding your mouthpiece with you pulling your jaw back from the position that the mouthpiece is formed at. If you don't snore, you are done and will be more comfortable. If you still snore, re-heat and move your jaw forward a little.