The rattling nose the mechanic at the dealer would be talking about is the plastic that protects the speedometers. I have been trying to fix mine as when i drive and only during certain RPMs it tends to rattle making a god aweful noise. Just try this, I know it probably is not what you are dealing with, but push the plastic towards the speedometers, basically push on it and see if it goes away. I thought it was coming from the engine bay as well but that quickly opened my eyes. As for sounding like an RC car in reverse...every honda i have owned sounds like that in reverse.