We have a 2004 R53 1.6 Cooper with the JCW
sound kit and ECU. Recently the plugs were changed at a service for the standard BMW plugs for a 1.6 Cooper. The car now seems a little "fluffy" and isn't pulling quite as well as before.
Previously we'd been using NGK Iridium BKR6EIX plugs and they seemed ok. However, always keen to hear what plugs other people have used and have felt that the change has been beneficial.
So, what's the concensus on which uprated plug to use on an N/A 1.6 Cooper Works?
Thanks in advance