[Aerkuld]

Not on a 997, but I have on my 996 which I would think would be very similar. I managed to do it without dropping the engine or removing the exhaust. It needed a lot of patience and an interesting array of socket extensions and knuckle joints. I recall that five of the six were relatively easy, but the forward-most plug on the left side of the car was a pain.

Next time the mufflers will be coming off. Definitely don't need to drop the engine.