El Capitan has a truss rod mainly because it is a heavily requested feature for a guitar of this size and scale length. Additionally at El Capitan's price point, many players insist on a truss rod for fine tuning the neck relief. The truss rod is easily accessed via the signature head 'shell'. Even without the custom machined rod, El Capitan has a very rigid neck; an intricate neck assembly with both Ekoa and carbon fiber as well as a custom designed carbon fiber neck profile. Generally speaking a stiffer neck makes for more efficient transfer of string energy and better sustain.