Regarding the ECU reset David, it doesn't really matter exactly when you do it, as Rob said. In fact, you don't *have* to do it at all. But it's recommended that you do (if I was you I'd do it as the last thing after finishing installing the new plugs, just before you turn the car on to check it fires up ok etc), to speed up the re-learning process so the ECU can get the right mixture etc going.