Basically the 2.0L ST170 has a plastic inlet manifold that is in two parts, the part that bolts to the head has silicone hoses on that is perfect for sticking some bike bodies onto. The ST170 manifold will not fit your 1.6 head so to do the conversion you will have to find a suitable way of mounting the bodies to your head. The 1.6 engines are very restrictive so the best thing you could do is up the capacity and buy a bigger engined focus.