We've seen products like that before - Windbooster comes to mind.
Their biggest problem is that they don't actually modify anything beyond the car's limits that are already there. Example: in "drag racing mode", all that really happens is that as you start to press the throttle, this device takes the partial signal and sends a full signal to the ECU, so that while you've only just touched the accelerator, the ECU thinks you've pressed the pedal to the floor. The "valet" function just brings the throttle on more smoothly, even if you jab your foot on the accelerator.
With practice, you can save yourself the money and just do it yourself (makes you a better driver too). You aren't getting any more power or economy out of the vehicle that a skilled driver couldn't achieve.
A performance chip that DOES modify the ECU fuel/air handling (eg Unichip) modifies the air/fuel rates (injector opening timing, rail pressure, turbo boost pressure) and you do get more power - at a cost. While plug-n-play, these performance chips cost over $1K each (some considerably closer to $2K). Over the remaining life of the vehicle, you might consider that expense as valuable for the performance gains or that it pays for itself in the economy gains.
For my money, the STX550 leaves enough Hiluxes and Amaroks for dead that you don't need to modify it at all.