Reddit mentions of Assenmacher Specialty Tools SP1412 14mm, 12-Point Thin Walled Spark Plug Socket

Here's the tool you'll need and here's the plugs I used for my 2008 R56. It's super easy to do! Hopefully that will fix your issue.

It took me about an hour and a half, but that was after already having done the dis-assembly to get to the spark plugs once before. Roughly half of that was actually changing the plugs and the other half was dis-assembling and re-assembling the air intake tubing and valve assembly before and after. You could definitely do it faster if you knew what you were doing - this was my first time changing spark plugs on any vehicle.

One thing I wasn't explicitly warned about and therefore didn't realize is the atypical spark plug diamater: 14mm. I tried to change the plugs last weekend and realized only when I got to removing the first spark plug that the spark plugs aren't standard 3/8 or 5/8 inch diameter, so my sockets wouldn't work. The HR engine (at least) takes 14mm - I think all VQ35s might take the same. I ordered this socket off amazon.ca since I was able to get fast shipping. It seems 14mm plug sockets advertised for BMWs will do the trick.

I ordered these spark plugs off ebay.ca, the whole set of 6 NGK laser iridium plugs was just under $100 USD. I made an effort to get the best plugs I could find, so you could probably find cheaper if you wanted. I think it's worth it to spend the extra ~$50 for the best though.

Yes

And don't forget your Spark Plug Socket

21 ft/lb or 28NM is the torque spec, as well.