Standard, these punch about 100bhp, which in a Fiesta Zetec-S, is pretty nippy. The old 1.6 Zetec and Zetec-E's were bollocks because of the tiny inlet valves and shitty tuning potential...however...
I've just finished a conversion of putting a C16XE 1.6 pre-Ecotec GSi engine into a Corsa (109bhp one). Engine runs perfectly (was dyno'd 111bhp shortly before removal).
Tonight I took it a run and for a laugh, picked on a Zetec-S...big mistake. It pumped me silly! I spoke to the boy and he showed me the engine, it's definitely the 1.6 and not a 1.7 transplant. He wouldn't, however, tell me what was done to it!
What sort of potential do these little lumps have, just short of replacing oily bits?