The funny thing is I get the buzz when it starts up but if I unplug the back right speaker the buzz goes away completely.

I had the exact same problem. Sometimes when I inserted the empeg, I would get an alternator whine (a buzzing sound that increases in pitch the higher the RPM of the engine). I found the problem to be a faulty (loose) ground connection to the empeg. NOT grounding the empeg will possibly fry various components inside of the machine, so I assumed that at least a small ground connection was being made. But the way that car audio works, you want to have at least the game gauge wire for the ground as you have for the power. If your connection to the ground isn't as strong as the connection to the power, this would be a possible cause of your engine noise. I'd recommend checking that the ground lead on your harnass is seated properly when you insert the empeg. To fix mine, I pulled it out completely, reinserted it, and bent the leads so that it wouldn't pull out again.

I seriously would recommend getting another harnass if the problems persist.

(O|||||O)