Thought I would add some useful info here about water pump replacement and maybe help someone in the future. I hope this is the right place for it. The pelican parts diy is pretty generic and makes things sound much easier than it can be. I hope you have less trouble than I did, but my wp was stuck. And by stuck I mean afraid-of-destroying-the-block/removing-metal-housing-in-pieces stuck.
The jacking screw holes are a great idea because you really don't want to be prying on the pump while using the timing cover for a fulcrum. A great idea until the flange snaps off anyway. Then your day goes south really fast. I blame the old WP design(sorry I didn't check brand before tossing) because I couldn't get a screw in the lower jacking hole to apply pressure evenly. (You should go from one side to the other with only a couple turns at a time on each side.) I tried tapping with a rubber mallet. I tried tapping with a 3lb blacksmith sledge. I used a pry bar on a 1x4 to spread the load across the front of the engine. I used half a can of PB Blaster over maybe 20 hours, evening to next afternoon. And I tried the monster channel-locks twisting the pump to break it free method. The POS may have laughed at me but it didn't budge.
What we (I called in reinforcements by this point.) discovered was that the battery hold-down bolt was the same size/thread as the water pump bolts and was long enough that the head did not hit the wp body. With constant tapping, while slowly cranking down the jacking screw, the pump FINALLY popped loose. Well, most of it anyway. Some parts remained behind:
It took some careful tapping and prying to get the remainder of the housing free then digging by hand and 45* and 90* needle-nose pliers along with sorta back-flushing through the small coolant hose to get all(or most) of the impeller pieces out. We reconstructed the pump like a puzzle so we would know how close we were. Some tiny bits washed down the driveway but I think it was mostly there.
Hope this helps someone before they get to the blown headgasket stage.
Yes, that's my next step since I'm pumping exhaust into the coolant now and cylinders 2 & 3 are nice and shiny looking from the spark plug holes. I really let my ADD get the better of me with this purchase. I'm having fun anyway but the whole point was to spend more money on the M5.
Good Luck,