Do you want to improve your upper body strength, pull up strength and the look of your upper back?
Then have a go at Sternum Pull Ups. I found this type of pull up in Charles Poliquin’s book The Poliquin Principles.
If fact, to train your back effectively you should do a variety of pulls up/chin ups. How do you mix up the variety? Well one of the best ways is to change your grip.
And, of course, you can make it even tougher by adding some weight to your body. (Using a weight belt, or by putting a dumbbell between your legs).