I've had a search on the forum and not found quite what I'm looking for. I have this weird smoke problem at the moment and had the plugs out to see if they'd give anything away. The plugs are showing the haynes manual description "small deposits, eninge in good condition, fuelling fine" or whatever, basically that all is well. However the plugs are made by unipart and have a gap of 6. I checked the haynes manual for the C20XE and it states that the gap should be 7-8 and that Vauxhall plugs should be used. I also have a slight misfire sometimes at about 3000rpm. I'm thinking the plugs could be the cause so need to change them. Should I go with the Vauxhall ones (probably expensive) or will something made by NGK/Champion do the job?