The 6.0 does not like "big" chips. They go like hell but are tough on head gaskets. There are only 4 small head bolts per cylinder and the high HP chips are simply too much stress on the head gaskets. I have a fleet of Fords on Edge 75 HP chips and AFE pro gaurd 7 filters, the result is an average 4 mpg increase over stock with a definite improvement in power. We are testing the Predator plug in chip and so far the mpg increase looks a little better. You still have to be careful when towing heavier loads, but we have seen head gasket failure on stock engines when subjected to lots of heavy towing, especially when the ambient temps are in the -30's or colder. A small chip and common sense driving will save you some money at the pumps. A big chip and a small IQ will get you a major repair bill. Just about any chip will function better with a decent intake and exhaust. One fix for the guys running big power with the 6.0 involves a set of head studs, on severe applications decking the block and heads along with "O" ringing the heads will keep the top end sealed nice and tight.
