The air pump is gone. Even with cats, its now useless. I'm more concerned that the check valve is now two way! Really needs to plug that all off. Can put some high flow cats if he wants although maybe they won't last as long. Those things really improved in terms of flow when Fox body Mustang 5.0s came out.
My other concerns with the disconnect systems is the EGR and the idle stop solenoid.
I'd want to be sure the EGR valve or passage is plugged if the system is not being used.
Presumably the air snorkel vacuum motors are still hooked up. If not that could really choke the air flow, maybe even at idle?
