To my knowledge, all Keystone trailers, fifth wheels and toy haulers have leaf spring suspension. Some of the "luxury models" have wet bolts, but most have "Lippert duralast plastic spring eye inserts" that are "guaranteed for life" but seldom last through the first camping season. The inserts are "guaranteed" but the labor to replace them is the owner's responsibility"... That's the reason most people who upgrade will change to wet bolts and heavy duty shackles.
Most Keystone "lower priced trailers and fifth wheels with tandem axles use a steel equalizer. Some of the more expensive brands do install the Lippert Roadmaster system.
While there are a couple of trailer brands that use torsion axles, I don't believe any Keystone trailers are among them. Typically, Airstream and that "class of trailer" is where you'll find torsion suspension.
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS