The Ecam is designed to be used with better flowing heads, intake, exhaust, maf, as well as a steeper rear gear. I think you'd be much happier using the 1.7's and the stock cam with the Cobra intake rather than the E cam. However, if your valve springs are tired, the 1.7's will make them more tired more quickly. They increase peak lift from .444" to .472" which makes the springs work harder. As for power increases - I've seen dyno tests that vary all the way from a gain of 18HP to a loss of 1HP for 1.7's being added to engines. It's virtually impossible to predict how much or if they'll help you. Your money is much better spent on the intake manifold - it is the biggest bottle neck to flow on the stock engine, and it (Cobra or have your stock lower ported by tmoss) along with a decent exhaust system and steeper rear gear will make a noticeable difference in the car's performance.