Well I just did mine and I sent them to a friends shop and he put them in his vac machine. It cleaned them pretty well. Still could run my finger on the inside and get carbon on it so I was surprised. I thought that machine would get all that out. Anyway I was not to thrilled with the cleaning so I went further. I work at an automotive shop. We have a 50 gal drum outside that contains our floor cleaner. So I filled one of our tire dunk tanks and then put the intakes in it and let them soak for about an hour. Then pulled them out and flipped them for the the cleaner to hit different areas. When the were done they were black!!!! I was like wtf, and you could rub your finger on it and the black stuff would be on your finger.
So I then took it back to our parts cleaner and wash them down good with that, and then out to the water hose for a gooooooood rinse. Let them dry, and then smoothed the gaskets area and took a little sand paper to the lower and the upper felt kind of rough from the cleaner. I just sprayed it with engine paint on the upper and lower, then after drying the next day put a couple coats of black spray paint on the upper. They looked pretty good, I did the TB and spacer the same, along with the IAC. My plaque is polished.
I am actually heading after work to pick it up from the place they got installed. I am looking forward to see the outcome.