I have a 2.0 blacktop zetec engine that i am planning on turboing.

What i was after finding out is, What are the mods that really need doing as a start?

Ive heard valve springs and retainers

But what else is there? Other than Pistons and rods, (Are the one from the states any good?)

I'm using a gt25 from a focus rs if that makes any difference.

I know they're really simple questions, but i never built a turbo engine myself. I've always just had ones that are already turbo-d.

cheers for any help

steve