They look to be running a Spring Over Axle life, or SPOA. That gives you about 5-6" depending on how good of quality your springs are. I like the basic kit from Sky Manufacturing or Low Range that gives you the cross-over steering and the wrap-around spring pads. You don't need longer shocks to start off and saves you quite a bit of work, they can always be changed after.
You can fit 33" tires with a SPOA, but it's tight. Most people add some taller springs as well.