A nice face lift st225 will set you back 6k here.
if you want a quick car that handles well, the arse has fallen out of the Renault Megane 2 RS 225 it will spank a Focus st170 Fiesta St150 and even a Focus st225 round a track.
but it’s not a Ford.
to answer your original question, the st170 will take a turbo easier in my opinion. But even done on the cheap it will cost you the same or more than the mk2 focus or Megane.