All the talk about it changing performance curves and what not is sales talk. Its basically like throwing a resistor on the IAT (intake air temperature) sensor to make the computer think the air outside is colder then it actually is. What that does is throw more fuel into the system just like it does when its cold out, you don't notice it when its cold because it actually needs to run richer. All in all yeah they work, but whats a 4% (AT MOST) performance gain with a 10% extra fuel cost and dirtier engine parts. (Rich running engines like to eat exhaust systems.) If you have money to spare, my motto is why not haha. But you will probably be disappointed.
