I am getting ready to do my first motorcycle tune up, my 2006 C50 Limited's first also. Bought a Clymer Manual on line and am ready to get serious. Before I lift the tank, I wanted to ask some "old salts" if there is a spark plug preference? The book recommends a set of NGK DPR7EA or a set of ND X22EPR-U9. Is there a difference between the two, or do I have more choices? Most of my miles are road miles with some city driving. I live in Florida, so its year round. Stock pipes, if that makes a difference.