Belkin TuneFM for iPod

I'd like to start using my iPod in the car during the commute to and from work.
Looking to get the best possible sound.

The factory radio in my car is Levinson, so it has a decent tuner, but, there is no iPod interface.

I came across this device from Belkin called TuneFM.
Anyone using this in their car? How does it sound? Any serious interference issues on the highway that may become annoying?

Thanks for any thoughts and ideas.
there is a factory amplifier in the trunk in my car. The car has a very good sounding Mark Levinson Lexus system. Really don't want to screw around with it.
I won't belabor the point any longer. I just know that running the ipod with rca's to an auxillary-in in the head unit, directly to the amp through an auxillary-in, or with a splitter between head unit and amp, will sound much better than an fm transmitter or even a cassette adaptor.
You might check and see if there is an aux in available for your head unit from the dealer. I bought one for my BMW 3 Series, and installed it myself--I think it was a whopping $15 or so. Its tucked up under the dash neatly. I also bought a cigarette lighter USB adapter, and a USB charger, and wired that into the fusebox, added a promount to slide the iPod into, and have an iPod install that looks virtually factory.