I have worked on a ton of these things and never had to fix anything beause of the MDS, that said, I make a nice aluminum plug you can put in place of the MDS solenoids to keep them from activating negating the need to pull heads and replace lifters. You can also just leave the MDS solenoid in the engine and unplugged and the MDS will not engage, if you don't do anything but put in the factory plastic plugs the engine will just run on 4 cyl all the time. The advantages of my plug is it keeps the MDS from activating, you can control exactly how much if any oil you want flowing to the lifter body, they look better if you have a manifold that allows you to see them, also if you bought an MDS engine and it did not come with the solenoids and you wish to stop them from activating then it is cheaper to buy my plug than 4 solenoids or pulling the heads and replacing lifters. I would post a pic butt ever since the last site upgrade I have not been able to get pics on here.