My 2011 D2-40 has little things like a monel heat exchanger that while expensive to replace, should never need replacement. I also really like the 130 amp stock alternator. After using the D2-40 for three years in my powerboat, the only problem I have had has been with the alarm sensor connector for the cable to the control panel. I have gotten into the habit of disconnecting and then reconnecting it every 20 or so engine hours. If I don't do that the connector works loose and the alarms go off. Other than that the engine runs flawlessly, is smooth and quiet. After the winter sitting, it started on the first crank