Ive been advised to replace my standard valve springs if i am running more than 5 psi boost on my blacktop zetec turbo, Is this correct? If so what valve springs do people recomend and will i need to take the head off to change them? I will be running around 1bar of boost. I should be getting it setup on the rollers in a couple of weeks so if they have to be changed i'd rather do it before.

Any help would be apriciated.

Si