I'm pretty sure the hood is the problem. As steve mentioned, our hoods are non-magnetic aluminum. So even though we're grounded to the frame, the we're lacking sufficient "ground plane" which is created by the nearby metal plate to reflect the wave.
Quote:
Who should use an NGP system? Here are some probabilities. Those with ...
* Fiberglass or plastic vehicles
* Hot air balloons
* Wilderness back pack frames
* Fiberglass pick-up bed caps
* Aluminum and/or fiberglass boats and canoes
* Aluminum and/or fiberglass cab-over campers (antenna on camper)
* Aluminum and/or fiberglass travel trailers