There is out there that I have seen a 16pot Caliper.
Only downfall to these is that some of the larger calipers running with multiple pots run separate pads.
The 16pot Caliper was running from memory 3 pads each side of the rotor, 2 smaller pads on the top and bottom taking 2 pots and a larger pad in the middle using 4 pots. The disadvantage to this is that if one set of pots fails you will have less braking power and you wont be able to determine what the cause is unless you pull the brakes off the caliper apart.
If you are going to go big brakes, best to stick with well known brands and pay the bit extra, I have heard good things about Justcraps G4 8pot brakes, and I have heard some bad things.
But a big caliper say 6pot AP Racing caliper running 1 brake pad either side of the rotor will give you better braking than a cheaper jap 8/12/16 pot caliper.