Personally I would keep your stock cam in too. If your heads have some miles on them then you will probably have to switch out your valve springs with anything other than a stock cam.. I know a lot of people with stock heads and springs would float the valves with the E cam. The X is way to much cam for your set up, if your looking at a letter cam the E would be plenty. Remember there is a lot more to chooseing a cam than lift and duration and bigger is NOT always better. And with stock heads the stock cam is a nice match.