Jodi is right Tower could care less. They make there money off of how much they sell. If the spark plug runs half ass and could possily cause your plane to crash but still run they will sell it. Its the same as if you go to a store and buy a $30 dollar helicopter that aint worth **** f it works it works if it dont oh well. Not saying that all their stuff is crap just if you can sell an engine that the customer can easily replace the spark plug if they wanted. They really could care less.