Unfortunately no to both. However you can upgrade the thermal compound that "links" the chips to the heat-sink.; I would recommend Arctic Silver 5. That is what I use and it has been proven to lower temperatures on Apple products by 5 - 10 degrees C. You can find that here. You can find the instructions for heat-sink removal and installation here. You can also improve the efficiency of your heat-sink by "lapping" it. You can find instructions for doing that here. That can buy you another 2-5 degrees C.

Thus you can dramatically increase the efficiency of your chips cooling system with out changing anything but the thermal compound and lower the temperatures by as much as 15 degrees C, which is a significant decrease in temperature