You can easily see how many sats you have by pressing the map button (to go to the map screen) and then pressing it again. It'll bring up a side screen with a little drop down menu. In the drop down there should be one called GPS viewer or something, it's near the bottom and it'll show your Sats and what kind of fix you have. 2 is ok for indoor (car park, garage) and 4-6 is what I usually see outdoors with my antenna under the dash.
Have you done the sharkfin antenna run yet btw?