Actually, each company has differnt techiques for packing as much magic smoke as they can into their motors. Of course, this is all negated if you run your motor too hot, thereby releasing the magic smoke.
On a more serious note, there are three main brushed motor "manufacturers" in the U.S. I use quotation marks because they don't really make the motors, as they are made overseas by Japanese companies. Anyways, the three main U.S. companies are Trinity/Epic, Reedy, and Team Orion(TOP). Each has their own (somewhat) unique design when it comes to cans, armatures, magnets, brushes, hoods, and endbells; but basically its the same core design.
Now, from what it sounds like in your post, you may be referencing "motor tuners". These are smaller companies that take a motor from one of the big three and tune it by balancing aramtures, aligning brush hoods, installing better brushes and springs, truing the commutator, polishing shafts and bushings, and centering the armature in the can. There are a wide variety of companies that offer these tuned motors, and most of them have their own thread in this forum so you can make an informed decision as to which motor to buy. Oh, and I'm sure there are plenty of people on this board that would be more than happy to suggest which company to choose.