We built one with .020, BSI head. Tons of torque and hp on the bottom end, very little up top. If you are running shorter tracks it is awesome. On the longer straights you will get passed on top end. I could pull the top 1.6s and FI hondas out of turns, but they would catch up and pass on long straights. Made for exciting racing. Keep in mind the 1.7 also runs the same airflow meter as the 1.8. So the airflow meter is much better on a 1.7 then a 1.6.