My thoughts, no on injection. Unless you are using it for a specific flavor profile, it is actually counterproductive to the process as it adds more water that is just going to need cooked out and increase the time even more. Even if there were some ability for that liquid to saturate the meat and moisten it during the cooking process (a theory which countless studies have seemed to debunk), a well marbled piece of meat (like your wagyu LOL) would be creating all the moisture that it needs during the rendering process. Which brings me to the burnt ends... I love burnt ends, but I think you are wasting that wagyu by not cooking the packer whole and eating the point sliced. Save the burn ends lesson for some choice (or even select) points.