I have been using a Garmin Nuvi 550 for the last two years and am very pleased with the performance and accuracy of the unit. It has a bright screen, long battery life, IPX7 waterproof, and is just the right size for my bikes.

However...

Unlike the Zumos, it does not have a line-out or bluetooth capability; it uses the internal speaker only. I haven't necessarily found this to be a BIG problem, but I was wondering if their is some way to hack the device to provide a line-out or bluetooth connection. Seems like I heard of something a year or two ago, but web searches have failed to give me a lead.

Anyone heard of such a thing?

TIA