Guys, unless you plan to use a Bluetooth connection for the audio output, don't forget to budget for a special motorcycle power and audio cable from Garmin to use with the 2820. This is a cable that has 4 bare wires on one end, and on the other end, it has a flat, 8 pin connector that plugs into the back of the GPSR. A foot or so down the cable from the 8 pin connector, there is a bifurcation in the cable that provides a jack to plug a headset into.
The benefit of this cable (besides the fact that it is pliable in cold weather and has a rubber cover on it that is fuel-proof) is that you get audio output from the same two pins on the back of the GPSR that are used to provide audio output to the little speaker on the 12 volt plug that you use when the system is plugged into a car.
Some folks have reported that there is a 'hiss' in the audio output if they plug a headset into the jack on the left hand side of the 2820. This jack is a new addition to the SP 2820 - previous models did not have such a jack. I kind of suspect that this jack on the side of the GPSR is not intended to deliver all the audio outputs (route guidance, beeps, attention tones, speed camera warnings, phone conversations, and music) to a headset - instead, it is intended only to provide music output to an external amplifier.
I think it will be especially critical to get this cable if you plan to integrate the 2820 into a larger audio system (such as an Autocom). The 2820 is a pretty complex device, sound-wise, compared to everything that has gone before it.
Here's the link to the Garmin website, where you will find the description of the special motorcycle power cable:
Motorcycle Power / Audio Cable for 2xxx series GPSRs. It costs $35. If you don't already own a Garmin motorcycle mounting bracket, you can save a bit of money if you order the package containing the special motorcycle audio cable and the mounting bracket (which comes with the security key and special bolts for mounting the bracket) - the price for the whole kit is $50, it is listed here:
Motorcycle mounting kit (unit bracket, power/audio cable, screws).
There's another conversation going on here in the GSer forum about this same topic (sound output from the 2820 when mounted on a moto), it might be worth having a look at it:
Garmin 2820 - first impressions.
Michael