Without the FCR Carb either cam isnt being taken full advantage of... I dont think adding the other cam before a carb upgrade will net any gains. Perhaps,drop power. A full exhaust and stock carb are great together. But,when you start adding any other mods to a DRZ motor: cams or big bore,you need the FCR 39 carb. The stock carb will not work in the rpm range the E model cams are designed.