[pbonsalb]

I just finished the driver’s side. Took me a little over 2 hours. No need to drain the coolant reservoir — it can be moved enough out of the way. But you do have to remove the ECU and a few harness connectors and release some harnesses and hoses from their holders.

Passenger side took a little over an hour. Had to remove the ECU and unplug the dozen harnesses attached to it, remove bolts from the intercooler reservoir so it could be shifted slightly to access the bolts for the wire harness tray that runs just above the coils (like on the driver’s side).

Anyone doing this, make sure you have the right spark plug socket. I did not so I had to grind down a 14mm deep socket so it was thinner walled and it took me a few tries to get it thin enough. The plugs are at the bottom of a shaft that narrows. Have a magnet tool to get the plugs out and to hold them when installing so they don’t drop onto the electrode and possibly reduce the gap. Be patient and careful. Spend time figuring out how to disconnect harnesses and to move wires.

I noticed several of my stock BMW Bosch plugs were loose - not really even hand tight. Those plugs also had some rust on the threads. Car has only 30k and is CPO so it was dealer serviced. Probably plugs are original and never touched. Gap seemed to be about 0.028. I installed colder NGK gapped to 0.022.

Don’t expect to notice any difference — car ran fine before. But this is one of those things that can make a difference in terms of knock limit and timing retard when pushing the car. Won’t be driving it until this afternoon. Update: noticed no driveability changes from the plug change, the tighter gap or the colder rating. Hopefully they help under high load conditions even if I can’t feel it.