Doesn’t do anything but it also didn’t hurt anything. Don’t worry about it if that’s what they did.
Heres what they did in a nut shell. They plugged the oil feed gallery feeding the drivers side lifter bank and then added the cross over to feed the drivers side lifter bank. So essentially they bypassed the OE lifter feed gallery and added a new one, because they think either the oil speed is “too fast” down the passenger side lifter passage and/or they think that pulling the oil off the passenger side gallery reduces oil losses.
If you study it out you’ll see it doesn’t fix anything, but the good news is it didn’t hurt anything either.
