YES you can turn the M10 into a 2.5 liter.

Metric Mechanic makes a 2.5 ltr. that puts out like 175+bhp.

But it goes for like $5000.00

Without forced induction the M10 will only be good for about 170 STREETABLE horsepower.

A more viable option would be to turn it into a 2.1 ltr. (2126cc)

Parts would cost around $800 new.

Your best bet would be to ditch the 318 and get anything else , then add a 318 or "td" badge.

Maybe even a 315 or 316 badge.

They do it in Europe all the time.

later,
Teaguer