Driving to work today, just got onto a dual carriageway and put my foot down, next thing, there's a big bang, something flies out the back of the car, and it misfires like a pig, managed to limp to work, open the bonnet to find the spark plug cover smashed, and a spark plug missing. Tried one of the others in it, and it won't do up, so it's stripped the thread.Bugger, looks like I need a new head.