I am trying to pick out my father's day present. I am going to get some new speakers for the truck and have decided on Infinity components for the front doors. I am looking at the 6810cs and the updated 6820cs and the only difference I notice is the 6820 is 2 ohm. Would this be a problem with the factory deck running it right now? The Infinity site says that 2 ohm is preferable. What do you think?