Trans Sport Performance Chip

Recently I've stumbled upon various "increase your HP, mileage" kind of "performance chips" for these minivans online.

Since there is very little information on how this "chips" are installed nor how they are supposed to work I wonder if any of you has tried such things and what were the results.

If you tested such an item please tell us how did u installed it and how did it work or didn't work on your engine.