cheers guys. it only had the symptoms of the way it was driving when it was real hot only happened twice.

i drove it to and from work earlier and after both drives (my work is only a 5min drive away on 30mph roads) the header tank was bulging where there was so much pressure build up. i done a block test at work that was fine, i also checked the radiator for blockages and all hoses and thermostat. the only thing i can think of that could be causing this pressure build up is maybe the header tank cap has had it? not releasing pressure.....

also it went for a set up a little while ago but seems to be running rough again so its booked in a totd for wednesday.

cheers