Man I really wish I had found this thread last weekend. I worked off and on for more than 4 hours on the number 8 coil removal. With all the reported hoses and battery cables removed and out of the way mine would not come out no matter how I rotated it. I finally went under the car and used a 2 inch truckers strap to pull the engine slightly over to the passenger side. Flexing the motor mounts a little.
This gained about 1/2 inch clearance and my #8 finally came out. I hooked to the rear of the oil pan and the pass side suspension by the ball joints. Cranked down the strap till I saw the engine move a little. That was what I needed in my car.

The above post mentioning collapsed electrodes. Probably happened when you installed them. Most spark plug sockets have a rubber insert to help you do this job or Champion sells spark plug installers that are like a rubber hose about 10 inches long and flexible for doing this job with no damage.
BTW: I used the Champion Iridium 9202 spark plugs. These are true Iridium plugs and are guaranteed 7 years unlimited miles. I have been told 200,000 is in reason.
I installed these in 3 previous BMW's we owned and trust them.
Thanks for your write ups on the #8, I sure wish I could have found it last week.....

Now while in there, I decided at 100,000 miles it is time to replace all fluids, filters and O'rings, gaskets for the valve covers etc. plus all Coolant hoses, the engine oil cooling gaskets and the Tranny filter and fluid $1,100 in parts and I bet this will be 40 + hours of my time before all is done.
But then I hope it is roadworthy for several more years.
Mark