As you can see, this is my very 1st post I'm looking at some Polks to install in my batwing fairing and want some input as to the sonic differences. The system is a JVC deck and Arc Audio 75w x 2 amp. Current speakers are Memphis Audio MClass 6.5" components. I like them ok but just looking at something different. I think I've narrowed it down to the MM651 or MM6501. I do have holes for tweeters so components work fine. Is their much sonic difference between the the two? Not concerned so much at a standstill but about going down the road at 60+mph with wind, road and exhaust noise playing into the mix. The MM651's can be found for quite a bit less and the crossovers are a bit smaller so they sound favorable. What if I throw the DB6501 components into the group? Cheaper still but probably not as durable for m/c use. The lower impedance MM line should really rock! Knowledgable input appreciated for the newbie.. Thanks !!