kbb is gauged by location as well..... cars are worth a lil more down south then they are up northkbb says they are worth 5500 and it is not a bad deal.. PI swpa is over rated, read my thead in this section on "When I see things like this.." and you will see why I say that..
he most likely means the intake has been replaced with the alluminium crossoverWould need to see pics and what is with the aluminum intake manifold? Did he tell you that to confuse/trick you? Have you actually seen and driven the Mustang?