I make mouthguards, but I am in Red Deer Alberta, Canada. I would give 10th planet guys a good deal on a proform Custom mouthguards. You really should'nt use anything but a custom guard as the boil and bite ones are quite a mouthfull and you are'nt able to perform to your fullest when you got a mouth full of spit.
I take upper and lower impressions and a bite registration, Then I mount the models on a machine that simulates the jaw. I vacuum form the upper model with the proform guard, then I use a torch to heat the guard and close the lower teeth into it making an index for your bite. This will allow you to have a balance bite, adequate breathing and shock absorbtion.
When you get punched in the jaw, it is the lateral deviation that compresses a nerve that tells your body that you don't know what your doing so it shuts your body down. Having a bite index will help prevent or at least lessen the deviation hopefully saving the fighter from being knocked out.
Also having a good bite registration can unlock your abilities, flexibiity and balance. If you have the bucks you can get an under armour mouth guard for about $500 or a PPM mouthguard like wanderlei silva for about $2000. The guards I make are not as expensive, but are based on the same Ideas.