I can actually hear the misfire through the zorst, then it starts to boost and it literally goes back to normal and really picks up...

2 of my mates have suggested it may be the cam as they have had similar problems with low down misfires

Just been out in it and taken the plugs out straight away and there was a horrible unburnt fuel smell out of number 2 plug hole, so I guess they may be right

I'll get hold of another cam today and start to rip the head apart...