re, thedak; I have two GMS.76's. I have one in a H-9 .60 Mustang ,bisson pitts muffler and an apc 13x6 prop.. I bought it when Tower started selling them.. I said for the money I'll try one. I use 15% , runs well.. but is no power house.. I found the carb a little sloppy.. not happy with it, so I changed the carb to an OS 7L.. Big differance.. Power is up ,runs great no problems. My second GMS .76, which was given to me.. It lasted about 9 flights.. was running it with 15% and a 12x6 on a big trainer ( LT-40), teaching my son.. During a flight at 1/2 power just flying.. it quit. Took it apart, well broke the piston rod on the lower end and spun out the bearning. Overall, Im not saying the GMS .76's are junk.. but .. you get what you pay for.. To compare engines.. my old old COMO .75 out runs the GMS's hands down. Glenn