I use MAS on trainers, cheap and bullet proof, APC on my glows and Xoars on my gas engines. On one of my gassers I tried the APC then the Xoar, a Zinoah, the Xoar spooled up faster and I got better RPM, the plane flew better with the Xoar. I have never tested any of the smaller Xoars so I can't say how they work on my smaller engines.