Do the best you can with what you have......on my sister's Z I sandblasted the plenum and it looks better than brandnew....cleaned up the ports real good. I blasted sand in all the cracks, crevices and holes I could. Know anyone w/ a sandblaster? You could clean the upper portions w/o any rags and simple green. I have some questions for you. Why did u get a new engine? And what made you decide on getting an ATK? How much?