Threw a new 55AX on the Burrito and took it out to break it in today(Got tired of the Saito 82 vibrating the covering so bad, it drove me crazy) Man this thing has some guts! Running a 13 x 4 that I had and it rips this little 4 &1/4 lb plane around. Just got 5 tanks thru it so still not really dialed in-pretty cold here so need a nice day to finish running it in. Will try a 13 x 4W also later on. Wondering what kind of RPM's I can expect out of these props.