They are built in Taiwan for Horizon Hobby. The needles are preset at the factory and the engines are run on the bench. One thing to remember is the temp/humidity in Taiwan is higher than most locations in the US and some needle setting will be required. Olso the engines are NOT "broken" at the factory since it takes about a gallon of fuel to get the engine running OK. Use the same method with Evolution engines like any other engine. They are very good once set in run properly.