I have a Glare Stomper attached to my Nuvi 765T and it helps. I have it mounted at the front of the tank and so its facing skyward about 30 degrees. Any less angle and the Glare Stomper prevents me from seeing the entire screen without ducking my head down a little. If I'm going to have to do the same thing with the 660 maybe I should just save my money and spend it for other things I want.
Screwball,
I have a zumo 660, a zumo 550 and a nuvi 765T. Yeah, I know... I'm a GPS whore.
Here are some comparison pictures of the three GPS screens, all with the brightness set to maximum
First, just sitting in the shade
And in the morning sun coming from a low side angle
I have cobbed together a sunshade for the 660 which does help, especially with the sun over your shoulder
Here's a comparison you might want to make note of. Pay attention to the difference in map details
The screen of the zumo 660 is brighter than the 765T. And the zumo 550 is brighter than the 660.
If you are considering buying a zumo, you may want to read my post where I have
compared the features of the 550 vs the 66X.