when i had my 1.7 puma I fitted a 2ltr mondeo throttle body and bored the inlet manfold out. I also had a cone filter which sat in a box to stop heat soak.
Put it this way rather my puma wasn't a fast one or the mods did fook all cause i had a play against a standard (well i think it was) and it flew past me ha ha ha.
I fitted st170 brake discs and trimmed down mk3 mondeo brake calipers. The best handling mods I did was 20mm axle/hub spacers on the rear and a strut brace which fits between the sub frame.
You could do the same mods cause the mk5 fiesta is just a puma.