MW, if your fimilar with tuning a cycle, the 5 Star is similar, but not quite the same.
I have the 5 Star on my 2012 class c, V-10 Ford based motor home, and tow a Subaru Crosstrek.
The 5 Star dosen't really give a great deal of added hp. Maybe an extra 10-15. But what it really does is re-program the trans, to the extent that it is a lot more "pleasureable" to drive. In a lot of situations it gets rid of the trans dropping from 5th gear/od, down into the "screaming 3rd" gear when going up a mild grade.
Don't know what type of rig you have, but if you have been on an xway at, lets say 65 mph, and started up a grade, lets say 5%, you know that after 100-200 yards, the trand will drop to 3rd gear, and rpm's go from 2300 up to 3600-3700 trying to maintain speed. The 5 Star lets it drop into 4th gear,while maintaining speed, and will,at some point if needed, then drop into 3rd.
And with the 5 Star, once you hit the crest of the grade, it will quickly drop the trans back to 5th, where with the stock tune it would stay in the "screaming 3rd" for a lot longer than necessary.
As for it "getting better milage" in a roundabout way it might simply by the fact that by not letting the tranny drop into 3rd, thus raising the rpm's by almost double, it uses a blt less fuel. On the flip side, just like a car or mc, making more hp uses more fues, so I guess it even's out in the end.
I have not noticed any less fuel usage or drop in mpg, but then again, I'm not too concerned with milage...it is what it is, pushing a 6 ton box thru the air at 65 mph, towing a 3200 lb car.
The added bit of hp does help, and is noticible under acceleration, like an entry ramp to an xway. But that extra 10-15 hp is about all your going to get. And, the 5 Star is tuned to use 87 octane fuel. Anything else is just a waste.
Other tuners may give an added hp increase by retuning to use mid or high test, but their after hp. Trans shift points stay the same, so it's not helping where our heave rv's need it.
If I owned a pickup with a V-10, and used it as a daily driver, I would look at the other tuners for pure hp gains, and I'm sure just the base Ford V-10 van or cut a way would do great with them. But our rv's come pretty much loaded out from the rv factory, almost at their limit, so just adding hp that requires mid or high test, without reprograming the trans to take advantage of the hp, dosen't help.
I've got around 5000 miles on the tune now, and have been thru the mountains in Va, Pa, NC, and SC, and the difference/change in "driveability" is very noticible. Personally, I'm very happy with the tune, and what it does, and I would buy it again.