Here's a good way to think: If this car part was so magical and increased HP, TQ, MPG, didn't hurt the car, is super cheap to manufacture, and is quite simple...why didn't any car companies ever create their own version? Or better yet, how likely is it that a small company had the funds to design this when the Big 3 automakers have several times the budget?
If it sounds too good to be true...it is. Look at legitimate modifications to cars; they all have a downside, which is why the car didn't come like that. Either they scare away older customers (huge wings, headers, sporty suspension), cost a lot, or hurt the cars reliability.
Tornados/Vortex things don't work, just like TB spacers and those $5 chips that you buy on ebay.
The idea of a TB spacer is that it smoothes the path for air to move easier. However, there is a legit way to do this in the TB; have it ported and polished. I seem to recall it costing about $100-$150 to have this done. Although it does actually add HP, probably not worth $100-$150. You can do it yourself if you're feeling brave and have a rotary tool/accessories such as a dremel.
Submitted for the approval of the Midnight Society