Run like hell from those snake oil salesmen. Those are just a resistor that you can buy for 25c at radio slack. They fake out the intake temp sensor into thinking the outside air is colder than it actually is, then advances the timing for a little boost.
The real chips cost 3 or 400 bucks and run a different program in the PCM for better power and tighter tranny shifts. Of course, programmers are more bucks but more versatile than the chip, consider that in your search for oooomph.
Edit: 100 HP? Ha!! That ought to tell you they are full of shit right there! Stay away from those tornadoes too, more useless BS. Even the expensive chips and programmers will only give you a small percentage of power increase with a gas engine. (diesels see way bigger gains) Still worth it to me, I've been running my truck "hot" since it was a month old.
One more advantage with the programmer- you get three programs based on the octane of gas you can find or afford at the time. If gas goes back to $4, you may want to take the chip out. With the programmer, just set it to 91 octane or back to 87. I got the guy to customize mine so even running the 87 octane setting I have no governor (set at 255 MPH) and tighter tranny shifts!