The FA-91 is one of the most popular selling engines in Saito"s extensive line of four-strokes. The .91 fits perfectly into most airplanes designed for .60-size two-strokes offering the ability to swing larger diameter props with more thrust than the two-stroke. Many pilots simply prefer the powerful sound of a four-stroke. Now Saito? is offering a new engine that offers even more power than the .91 but that"s similar in size and weight.