Is the intake manifold on 03-04 cobra coated? Trying to get it clean

[Vanilla Mustang]

Hi,

Does anyone have experience with the aluminum manifold? I am tring to get it clean but it almost seems like it is getting dirtier. Let me know if you have any suggestions while I have it off the car.

 

[Vanilla Mustang]

or maybe someone knows a good aluminum cleaner?