I purposefully left the GPS antenna off today to because I need to find a proper place to put it in my car. I've read here that the Pioneer antenna can disrupt the iPhone more than help it.

If you guys did a new install today, would you guys keep it on, or would you just say no and leave it disconnected?

for tomtom, i had to disconnect the AR2 gps, then all was fine!!

I've disconnected the AR2 GPS - tomtom now works and the speed indicator on navfree also finally works.... Difficult to see how the AR2 GPS provides any benefit!

If you're still looking for a proper place for the GPS antenna it may work well under the dash. My last car had its factory GPS antenna on a little platform underneath the dash. There was no metal or anything that could interfere above it - just the plastic dashboard top.

For the AR2 installation I just did on my current car, I simply stuck the GPS antenna to the top of the radio itself (it's magnetic). The radio fit just fine in the dash. The only thing above it is the plastic top of the dashboard (like my previous car).

I used to use Navfree like mjellison1a and I noticed that the speed indicator was intermittent. So for him, removing the GPS antenna either actually did fix this issue, or it's just working intermittently like it did for me.

I use Motion X now. The GPS tracking is 100x better/faster/more accurate than NavFree and it's directions are dead on, unlike my experience with NavFree. This is for the San Diego, CA area.