wounder if any 1 can help my cosworth had a bad miss fire when it peaked at boost i got told off motor scope that i had to change my plugs. Replaced my plugs with chamion qc57c the miss fire at peak boost has slightly gone but still there and it idles realy rough. I rang motorscope back and they susgested regap the plugs so i did to 20thow but still no better can any 1 help cheers tony