You might be able to better match the ambient with the level if both the ambient value of the level and the entity matches. I'm talking about using materials and not setting it in WED. I've pretty much gotten everythign to match(levels, models, entities, flat surfaces) using the one that is in the templates folder. It's global, but works for quick tests. Just fiddle with the values. Once you get the hang of it...you'll appreciate the extra control.
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The bumpmapping is nice. Thanks for the contrib.