well, while i am waiting for my m6 threaded rod for my z upgrade on my printrbot jr, i have been looking at other upgrades that i think i would like to do. i think that the next most obvious thing is to upgrade from the included belts and pulleys(which i think are T5), to the GT2 belts and GT2 16 tooth timing pulleys. Any thoughts? and will this require step adjustments as my z mod will?
We used to use XL belts, now we use gt2. I honestly didn’t see a big jump in quality, but perception wins out. 
have fun building and experimenting! Share your results!
Brook