Going from stock to 1.6's wont net you any list, so you are reducing friction for 1.213456hp , roughly.
Going to 1.7's you will now add more lift to the cam. Take you current cam specs and do the math. Either divide TOTAL LIFT by 1.6 then multiply by 1.7 . Or take LOBE LIFT and just multiply by 1.7 to see how much more you gain.
p.s. Watch the lift numbers, as your valve springs may not be able to handle that much lift (either bind at that travel, or not enough pressure to close the valve).