Factory box is much better then previous factory boxes (7.3). I am getting ready to switch just because I got a smoken deal (Cheaper then a new filter) on a used one from a customer of mine and I wanted washable filters. Unless you have money to blow I would stick with the stock box.
Chris
The diablo (or at least the older ones) are known to pop head gaskets. Listen to Gene (WeWeld) after all he has the fastest 6.0 in the world... At least for now... Custom Tuned SCT hands down.
I just go straight to the International Truck dealership and get them for half the price of FMCO.
The kit you want is really for the VT275 even though our engine is a VT365.
Int'l #: 1847170C92