Coop and Race Yes I am driving an EVO again and you have the name correct.
I shim both the pinion and the ring. It takes time to do it properly by taking things apart so much but it is the only way to get it correct. You also get a feel for hom much a box or gear needs by doing it. I shim the diffs also as the pinion wears you have to to keep the gears from skipping under braking. As for shim size I believe it is the 5mm shim set it comes in .1,.2,.3 sizes. Also with the assembly and reassembly be careful not to over tighten the 3 screws holding the case front on.
JFC I think Tech has one but I can't remember either.