I am thinking of fitting a power boost valve such as this eBay listing, to the J16's Sigma engine to hopefully sharpen up the engines pick up and correct a small flat spot.

Does anyone have experience of doing this?

What do you do with the existing rail mounted valve? Remove it and fit an adapter?

Does the boost valve need a vacuum source to work?

Any input would be appreciated.

FORD Puma 1.7 Zetec 97-2002 FSE POWER BOOST VALVE | eBay

Hummm....in my opinion it's just a pressure regulator...any adjustable reg will enable you to get a richer mixture......but, it will add fuel over the entire fuel map, which is not always what you want......Assuming your injectors are up to it, a remap would yield much better results than just throwing in more fuel everywhere. Jmho of course

These did work at the expense of fuel consumption on 1980s Efi engines but modern engines run closed loop and self-learn the characteristics on an individual engine.

The ECU will detect over richness initially pull back the short term fuel trim, then after a few run cycles as the ECU re-learns the engine it will pull back the long term fuel trim which will put you back to where you started.