I've done a few of these and will add on to what MaxQ's thoughts are. Not all wagyu's are made the same, some of them have more bloodline to them, have been feed a different feed regiment, etc. Because of these factors there can be 10* difference in finish temp. You will find that times will be close to what you have done with your prime briskets.
Like Chris said, I've never had a brisket done at 190* in my life, but I too cook a little hotter than 225*, so that will factor into your finial temp.