How can I tell the size of a turbo housing? I was looking at some HX40W cores and notice that in the inside of the exhaust housings some had 18 and others had 16 stamp, the same appear on the outside emboss next to what look to be the housing part number. The Intake housings had an emboss circle with a number, #11, #12, #14. Are this numbers the size? I have tried calling Piers but I always get his answering machine, I must be one of hundreds calling him for information, thats what happens when you are one of the best. Piers, keep up the excellent work!