I have the ScangaugeII and the temp is very consistent once warmed up, right around 181 so far. I image it will go up a little as the ambient air temp goes up over the summer. That would be my only concern, and I doubt that it would be an issue except under extreme conditions. I would also have to look where the AC unit is located, that might be an issue too.
I agree you would have to fill the lower grill to make it flush, but it is a pretty big area and might give more gains than the upper grill. I only have the running light recesses, no lights so that is less of an issue for me. There are no extras on mine. It is as stock as you can get it.
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