2% (salicylic) and 10% (BP) are as high as you'll get for facial preparations without a prescription. While I understand the feeling of, "but if I use MORE, my face will be CLEARER!" it's also very dangerous because you could strip the skin off your face, cause allergic reactions because of the higher dose, dry your face out dangerously, yadda yadda.
The only thing I've been able to find with a higher dosage of salicylic acid is wart remover. I know it sounds gross, but that's what they use to take those suckers off. It works, yes, but it dries the heck out of your skin for a couple of weeks. And when you're talking about the more-sensitive skin that's on the face, you're really risking scarring and other non-fun things.