I can't say about these chips.
but I'll consider something that I do know about.
consider the famous star chips (http://www.morego.co.uk/index.php
yes, they work, and some.
they also cost a lot, take that twenty dollar amount and multiple it be a large number.
I don't know this van at all, but according to wikipedia it's power output at the engine is 150HP...
which makes me wonder why the auction has a big banner saying that your car can be 'tuned' with their plastic box to 100HP?
The chips work by remapping the engine timing via the ECU, this is not a fix on its own, (read the BBR site and you'll see that the real deal star chips do a lot more besides messing with some engine timing fuelling issues). but altering the engine mapping can alter the fuel consumption.
the long an the short of it is this.
the engine mixture, and engine timing is controlled by the ECU, the ECU is just a computer, and it can be re-programmed.
but there are some things to consider...
1, when ford made the car, they did know what they were doing!
2, you may void the warranty - despite the fact that the auction says that you wn't
3, is this actually tested on your vehicle? I doubt it, because of what I'd said about the power ratios above, if this had been developed for, and tested on your vehicle, then you'd have thought that they'd have been able to post some accurate figures rather than massive claims.
with that banner as well, +30mpg?
is that extra to what you already get? in which case I doubt it, or is this what you should expect with this modification?
if it's what you should expect then why not just get a more economical car? rather than waste money on trying to make a heavy large engined van more efficient?