I just ordered the lime green colored Shock Doctor Double power mouthguard. It's suppose to protect the upper and lower teeth. I haven't boil and bite it yet as I'm reading the instructions on it. It says as soon as I take it out of the boiling water, fit it in my upper teeth first. And then bring my lower jaw forward and bite down hard. Bringing my lower jaw forward, hmmm..... Wouldn't that give me an underbite? I'm bringing my jaw forward as of right now and it feels awkward and sore. Imagine what it feels like when I'm biting down on a mouthguard in an underbite position and getting hit. OUCH! Are all double mouthguards fitting instructions the same? Why can't I just normal bite it without bringing my lower jaw forward? Kinda strange if you ask me. Anyone using a brain pad or shock doctor double mouthguard? How did you custom fit it?