hi, I have been trying to research this to death. I am considering buying a FMF powercore 4, for my yz426f. My direct question is, do I need the PowerBomb head to go with it. Every wheres I shop, they don't include the head. In my mind, you would need both. I never bought and exhaust before so maybe I'm delusional. Second I'm also upgrading my cams, to HOT CAMS stage 1 with twin air intake. I believe this should increase my power all around. More air coming in, more air coming out. And of course I will need to re-jet. Thanks. Kevin.