This setup is a vehicle system correct? Yukon being a GM vehicle, like a SUV on steroids big lots of room to install a nice system if you choose too. As for needing a 2nd amp, I would think so, as for running a 2nd wire harness I would believe so too. But you didn't say if you're pulling out the original speakers? Or if your keeping the OEM in the dash. You may want to jump over to Crutchfield there a online company they deal in car/truck audio and video also, you can chat online with one of their associates or even give them a call. I use to use them back in the mid 90's. Very good customer service before and after the sale. Now maybe you'll have some members on AH who can help. Have you tried Googling to see if you can find, some audio forums that are car/truck enthusiast.