The difference between the 160 and the 170CDI is inmense, I think the 170CDI have around 30% more power, verticals on the 160 might be at full throttle were the 170CDI will be a 3/4, and if you fly with a wind of 30Km/hr you will really appreciate the power of the 170CDI.

Keep in mind, the 170CDI is the most powerfull of the 170's where the 170 converted to CDI are close to 10% less power, the 170CDI have a special piston called hyper piston wich boost the power, any 170 can be upgraded by replacing the piston anyway.

Regards

Alejandro P.