I own a mk5 zetec-s with the std 1.6 engine... and its not exactly slow.. its not a supercar beater though either, but its still quick-ish...

Check for rust on rear arches as said above.... luckily mine is all clear

Get a phase2 aswell... better all round than the phase1's

Puma conversions give you like an extra 20/22bhp i think..., so the zetec-s goes from about 101bhp to about 123bhp...

Would prefer the 2.0 blacktop engine than the 1.7..but probably cost a fair bit more to drop in and get running than the puma lump.. plus the 2.0 only has about 8bhp more than the puma engine