Perfect for 3D, precision and sport flying! It's a fantastic way to ratchet up horsepower for more flying fun! The 120AX, which boasts 20% more displacement than a .91, can turn bigger props with ease, resulting in improved 3D, precision and sport flying. Boost your plane's performance, without compromising weight — bolt in a 120AX and see the difference for yourself! With the 120AX, there's no need to buy an expensive aftermarket muffler! The included Power Box™ muffler comes with two adapters — one of which turns the muffler 90° to become a "Pitts style."