A few observations -
Alot of these 'magic boxes' are made for rice boys to impress other rice boys. It's unlikely they will do anything for a stock or lightly modded motor. (intake and exhaust)
Install one wrong - cross a wire splice - and you may blow the ECU. Just a little current in the wrong place will easily fry a microchip. Ask the dealer for a new computer - sure. He'll ignore the cuts in the wires. Wanna bet.
If you build a serious motor then you will need a programable ECU and the instruments that go along with it. A/F ratio, fuel pressure, knock sensor, boost-vacuum, laptop for downloads and...
Would make one heck of a street racer but would suck off-road.
So you want exhaust headers? Great for top end power. But everyone says they want low end torque for off-road applications. For low end, a header made with soda straw diameter tubing would be super. But it would choke mid and high end power. How about a big old sewer pipe header. Great top end, low end would suck tho. The factory gave me a header that is tolerable... why mess.
Wanna know how to fool a dyno? Ask some of the go-faster suppliers - they know. That's if the stuff ever gets tested. Dyno time is expensive. They cannot afford to check every piss-ant little item that they sell. They'll make promises and take your money - it would cost you more in dyno time to prove them wrong.
dave and xtoy - it's your $$$