An upgrade to the original StealthGao, created by adding Ul-Tech Engine drive nacelles to the wings and a spar of unknown purpose to the back of the craft. These option parts are collectively known as the "Space Booster". StealthGao II forms the back unit of Star GaoGaiGar and later GaoGaiGo. Its nacelles also contain a pair of detachable pieces known as Phantom Rings, which are designed to interface with and enhance the power of GaoGaiGar's Broken Magnum and Protect Shade attacks, turning them respectively into Broken Phantom and Protect Wall. The Space Booster parts can be jettisoned if necessary, leaving a craft identical to StealthGao.