TBH it has more chance of working well on a Turbo car than a NA car as it tricks the ECU in to thinking the car is running cooler and adds a little more fuel and runs a little richer.
Still a bit of a bodge though
run to rich and run the risk of bore wash, I also dont think its complex enough to match you fueling as revs / boost increases.
It also mentions it advances the timing
If your adding more fuel, you can then retard the timing to increase power as there is less chance of detonation.
Dont think Id risk running one on my car