Is yours a silvertop or a blacktop as the longer springs don't fit either inlet or exhaust on the blacktop. Twat.

For any one reading this at a later date.

My head is a 2004 2.0 Focus zetec from a crate engine.

Standard springs are all 44.5mm long.

The st170 head is from a 2002 and there are two spring lengths.

45.25mm

47mm

The 47mm are coil binding at just before full lift.