How hard it it to switch to a dual fan setup.. I know that i need the wiring harness, but will it pulg and play?

 

From a single fan set-up? No. The single fan is set to come on at a certain temp. (fan switch is in the head) or when you turn the A\C on. You can plug THAT plug to ONE fan in your new 2-fan setup, but the other fan will have to be wired from a different sensor (or splice in to the one already there). You can get the connectors at Pep Boys. Put the new fan on a separate relay.