If you are thinking that you must have a NIM for a GPS to work on your bike then you are not alone. I get dozens of calls every month asking this questions. The simple answer is NO you do not. Lots of people think that they must have a NIM in order for the GPS to work. This is not the case.
You can mount a GPS route the output from the GPS to your Auxiliary Input on your radio, place your radio in the AUX mode of operation and you will hear any thing that the GPS is transmitting such as Turn Prompts, MP3 songs, a phone call, XM Radio, Weather and Traffic Alerts. XM, Weather & Traffic if you have the 665.
If you install a NIM then your radio does not have to be in the AUX mode in order to hear Turn Prompts from the GPS (Turn Prompts Only). The NIM will automatically interrupt the output of the radio so that you will hear the Turn Prompt and then return the radio to it's former function. Having said that if you want to hear MP3 songs, a phone call, XM Radio, Weather or Traffic Alerts (if you have the Zumo 665) then the output of the GPS must go to the Auxiliary Input on the radio and the radio must be in the AUX mode. You can not take advantage of all the GPS output functions simple by having a NIM. The NIM is only good for Turn Prompts.
If you have a NIM and you also want to be able to hear all the other functions of the GPS then the Audio Output from the GPS must be split so that you are feeding both the NIM and the Auxiliary Input on the radio.
When the factory installs the NIM they do not connect the GPS output to the Auxiliary Input on the radio, this is some thing you must do yourself or have the dealer install the Y-Splitter and audio cable.
Jim