By "plow" do you mean it is oversteering?
51 is a pretty high max. Considering the list of mods you have, I would suggest trying something like 44 in the front and 38 in the back. See if that takes away some of your 'plowing' effect.
From a tire wear standpoint, most of the time you tend to get the most even wear under general use conditions if you are running at about 80-85 percent of the max for the tire in the front, and normally a bit less in the back. The back varies a lot more, though. This is on front engine, front wheel drive. It differs for other arraingements.
Also, how you drive comes into it, so that is just a rule of thumb. If you are doing a lot of hard cornering on less than even pavement, you might find that this is wearing the sides faster than the middle, so you would increase the pressure a bit. If you are doing a lot of straight, fast stuff, you might be getting too much wear in the middle, and need to decrease the pressure a bit.
In general, you need to play with it every time you try a new make/model to get a feel for the differences. Also, whenever you change the suspension, such as the 26mm RSB you are thinking about, you will have to test around on pressures again.
pax, smn