240 ish is about the most on a nasp silvertop zetec

Blacktops slightly more

ST170 slightly more again due to head flow

Dont speak to Dunnell as the guy is an arrogant clown

Qizzed him before about stuff and he was clueless but made out he knew everything

You will need throttle boddies, alot of headwork, huge cams, high comp pistons, steel rods and a dry sump

Not a cheap option, If your going to all this expense start with an ST170 engine or completely different engine as you will get more BHP per £ spent