What is a safe product to use for scrubbing the inside of powder coated intakes?

 

A toilet brush and any number of soapy solutions is fine, I use simple green.

 

Q: did you have the inside powder coated or where they coated already when you pulled them from the car?

In post # 14 I show pictures for the number (1) intake that I took of the car it has a coating on the inside that I'm going to leave alone, the out side coating has now been peeled of completly and I plan on blasting the outside only.

The number (2) intake manifold (did not have an inside coating) and it will be blasted in and outside followed by scrubbing until clean

 

It was a 1990 S4 intake, not a GTS intake such as yours