I'm pretty sure that GMS makes the engines. People seem to swear by GMS engines on this forum

i had an MDS .40 on my Yamamoto, ran sweet for about a couple of flights but then it wouldnt start, was cutting out in flight and generally became a P.I.T.A, tried everything, new muffler, new glow plug, different prop, different tuning (i always ran it slightly rich as it was still a new engine) but all to no avail

i ripped that horrible thing out and put a used OS .46LA in there from ebay (be carefull buying used engines as mentioned above, but for £30 if it goes pop then its not a big loss) and that OS has breathed a whole new lease of life into that little trainer, reliable, easy starting, and pretty powerful

I have owned many sizes of many of the brands discussed here. over the years Id say certain engine sizes in certain brands have developed bad reputations. this was often errased with introducing new series later on.some of the cheaper imports did not hold up too well at first but now seem to do as well or better. it depends on what you want to do withit.for the price the sport motors like TT are hard to beat. although it is more rare now a days, bad engines do sometimes slip through. this is especially noticable in poorly assembled carbs & parts not to specs.