fecarman,
You should be careful as a lot of people here may have different personal opinions regarding CF. While maybe useless for you, I don't think anyone paid what they did to get the CF would share your opinion.
We've done many different things with the audio system of the GT. Frankly, it is the least fun parts of the GT to work on because space is frequently cramped and awkward. In terms of sound quality - the OEM Mac set-up is pretty darn good. Admittedly it is light on features and iPod control. As others have mentioned, you CAN connect an iPod by simply installing an RCA to mini-stereo plug to the pigtail RCA jacks at the back of the MAC H/U.
To get more features, virtually any aftermarket single DIN stereo will fit in the GT. There are numerous units out there with full iPod control, bluetooth, satellite, etc. capabilities. Our experience is that alternate head units don't play nice with the MAC amp and I would recommend that you consider that you may need to change the Mac amp if you change the headunit. It's not an absolute necessity but if you are an acute audiophile, this will likely be needed.
Finally, you can go the double-DIN route as shown in CF but also available from Kip in the OEM silver cast aluminum. More possibilities with these units for NAV, back-up camera, etc.
PM me if you want to go deeper into any of these alternatives and I will gladly share our experience.