If you install the head on the motor, then you can't get to the upper bellhousing bolts because there's a thermostat thing sticking off the back of the head. And you have to have the intake manifold off to install the starter, and installing the intake manifold with the head on in the car is a bitch cause you can't get to the lower nuts that hold it on. Turbo manifold can be done with everything in the car, but still easier with it out. In my case, I just pulled 10 head bolts and removed the manifold/turbo/head assembly, and then put it back on. So I never took any of that other stuff apart.