I'm afraid with the 1.6 you wont get a figure like 160-170bhp without spending A LOT of cash.

My original 1.4 16v Zetec SE had a few minor bits like Cams, unichip, manifold, exhaust and a hefty sum of Nitrous. She guzzled out 145bhp on the rollers, but then I got bored.

The same spec on the next engine I had, which was the same as yours, a 1.6 16v Zetec SE lump. She could barely scrape the 150bhp mark, but with a bit more Nitrous, she would...but it doubt it would have lasted very long.

There are other options like a throttle body conversion you can get. Not loads of options, but either way your talking big bucks...