A 7.3 with a tuner is not like a 6.0 with a tuner. An SCT will offer him increased MPG, and firm up his shift points. I have one on my 2000 7.3 Excursion, and I love it. I have a SuperChips and a Banks Big Hoss as well for it. Have him check his PCM code, and if he has the same as me, I would sell the Big Hoss. It is a lvl 4 100hp chip. The chip is a hardware chip that slides on the PCM main board. I also run a Six-Gun stacked on the SCT, and I used it stacked on the Banks. In my oppinion, the Banks actually makes more low RPM power/tq, but the SCT X-Cal2 will out run it at higher RPM's. I think for towing and around town use, the Big Hoss may well be the better option, but I like playing with differant tunes so I am using the SCT now. I also have an old SCT Xcal (Not the X-Cal2) that has custom files, and they are some insane mean files for pulling, I will be testing them this summer on the track. If your bro in law wants to talk a bit, have him give me a call Thursday evening, I am out of town this week until then. 724-462-3669.
I can tell him what I have tested and played with on my 7.3 Excursion, and what my opinions are.