I am not sure :4-dontknow: You already have the lift with the cam, with the 1.7rr you will be lifting them more. Shorter push rods may work, BUT again bad idea. You can get 1.6 rr from HS also. I would really do some research on this before you install the cam and the 1.7rr. One thing I do know is that you can install the 1.7rr with the stock cam no prob, The 1.7s gives you lift and makes the computer see a bigger cam.