Seems you've never heard of the term 'porting'. The removal of material to improve flow using a die grinder, dremel, etc. Many people have found it extremely easy to do that to plastic composite as well as aluminium manifolds/heads. So no problem with a 65mm billet TB. What would you have done if the ST170 TB did have the same bolt pattern, just leave a step?

Your confident a ST170 manifold flows better, huh. But you've not actually tested it or it seems, even read the few books reporting tests. Sounds like a bookies dream.

Rather than start a new thread with your NEW question, you decided to make an incomplete post in one 2 years old.

You then started discussing a 2.0 Focus Ghia (Blacktop), now your talking about a silvertop. As I said, I've had quite a few different engines, heads and manifolds through my workshop and I document them all for future reference. I'm reasonably confident I know their dimensions and porting that works. So since you know your right (using guesswork), please carry on, I wish you luck.

Martin