With the GMS .47, make sure that you leave the needles set as it comes out of the box.

Tighten the fittings ( but watch out not to overdo it as some are easy to break or strip ), especially wherever you see one of the red spacer/washers.

After you've run the engine for a tank or two, plan on tightening down all of the cap screws with a hex driver.

If you find that the muffler "spins" on you, push the muffler's exhaust hemisphere firmly in while tightening the long screw. This is what actually holds thing in place... then once tight, tighten the provided nut.

Check the muffler nipple after the first few flights. Make sure that there is no gunk clogging the pressure fitting.

I find that the GMS engines need to run with the low end a little leaner than what one would normally set for a typical 2 stroker, but at the same time with the high end a bit richer. This smooths out the midrange transition.

Once you have it broken in, it's a good strong engine.