Brett, when talking about a boxblade, you have three digging surfaces: Scarifiers, inner blade, rear blade. When you just say "digging," it's a litle vague if you don't say what part you are talking about. Certainly, if you shorten the toplink, your scarifiers will dig in more; however, your inside cutting blade may lift completely off the ground and not cut at all. The same goes for the rear blade.
Tilting the box by lengthening your toplink will get the inside blade sitting at an angle to dig in until the sides of the box become skids. In very loose soil, the sides will just bury up and you'll find you cut so much you'll quickly have a full boxblade. When you are blading in reverse, the rear blade becomes a mini-dozer or grader blade. Again, extending the toplink will cause it to dig in. The type of soil and the size of your tractor will really determine what is the best angle to use for all the different jobs you can do with your box. /forums/images/graemlins/cool.gif