High protein & high gluten are mostly the same thing (for our purposes). You can add vital wheat gluten, but it's not the best thing to do. The best flour for pizza, really depends on the style of pizza. Almost any flour can be turned into a good pizza using good technique. Technique is the most important thing. For a NY pizza, most people use either a High gluten flour (13.5-14% protein) or an italian 00 flour which is usually 11% (00 is also ground finer). But some, use other flours, such as Bread Flour (12.5%). I've used all of these, and I prefer Bread Flour the best. But many on the board will disagree with me. If you click over to my page, by clicking the little globe under my name, you will see photos of pies made with practically every flour. Yet the pies look similar (not exactly the same, but very similar) and all look good. To make dough, you must have protein and work or 'develop' the protein by using good mixing techniques. If you have a lot of protein and don't develop it well, it's a waste. If you have little protein and know how to develop it, it can be great. So I recommend to everyone to start with a good flour, such as King Arthur Bread Flour and from there spend 90% of you effort on understanding technique, rather than experimenting with many kinds of flour. Later, when you've got the process down, then go back and switch flours around and see which you like best.