Help me choose a car audio system.?

I would go with the kenwood. Try to talk your friend down to 250. MTX is a great brand but they are good because of one sub they have made and thats the MTX Jackhammer. Not the little jackhammers im talking about the 24" sub and thats all they make thats good the rest is just all in the name. Kenwood makes some nice stuff that can handle whatever you want to put into it. Another good brand that can handle anything is kicker. I hope this helped