"That Angle" is all about the suspension and how much it can flex. The suspension keeps all the tires on the ground, which means you'll go further since you'll have more traction. Depending on the 'lift kit' will depend on how much more flex (or angle) your truck will be capable of.
Btw, on that show your talking about... They used "Revolver" Shackles to allow the jeep to go further up the ramp.

93' Toy xCab
bobbed > 22rEB > w56 > stock duals > SAS > 4.88's > 37's