Is there anything special to know about coating these in ceramic. I assume I will just tape off the 3 main flanges on their face and just shoot the outside per customer request to not do the insides. How much should we get for these housings. I also have 4 pipes (aluminum) about 4″x 2.5’and 2 pipes 4″x1′. The short pipes are ceramic outside only and the larger ones inside and outside.