Just wondering what people think of them?

I've seen a couple around. What do the do specifically and are they at all worth the install / price?

 

they control the vtec changeover point and usually the air/fuel ratios as well. unless you can get the car dyno tuned, its not going to do you any good, and if you dont know what you are doing, you can seriously damage your motor.

 

i have the VAFC-II in my car, its sweet. its tuned by a local shop here after i got my turbo stuff installed.