Agreed, I use the ASL iPod/iTouch Charging Auxiliary Booster/Line Conditioner
The benefit of the one the
OP mentioned is that when you are on a call that the persons voice comes through the car speakers.
I have used both and the Charging Auxiliary Booster/Line Conditioner is great.
Its very easy to put together, you just need to take the plastic off the side of the console by removing the gear surround. The undo the bolts, take the tissue box holder out, find the wires to plug it all together, put it all back and its done.
About 30 to 45 mins to complete. A phillips screw driver is all you will need if I can remember correctly.