I had Best Buy install the Parrot CK3000 Evolution with the Multicomm in my daughter's car. She thinks part of driving is talking on the phone. One hand was always holding her phone to her ear while driving. She needed a good hands-free unit to make the road safer for others.At low speeds, it worked great. It also worked great for me at high speed. The callers could hardly tell I was on a hands-free unit even at high speeds in a small (noisy) car.But when my daughter used it at high speeds, people would tell her she was very hard to understand. There seemed to be a scratching static of her higher voice when the road noise increased. I theorize that the Parrot noise cancelation was canceling out too much of her voice when road noise increased.I added a 10 ohm resistor (from Radio Shack) in the microphone wire. This did the trick. The extra resistance lowered the sensitivity in the microphone resulting in less pick-up of road noise but still great pick-up of her voice. Lowering the sensitivity resulted in less need for the noise cancelation to work so hard. It still cancels most road noise, but does not lower the quality of her voice. You almost can't tell she is on a speaker phone. With the adjustment, this becomes an amazing product.