Awesome post Dave. That would go a long way to explaining why the "150 Watt" 3way 6x9 Blaupunkt (spl?) speakers I put in the doors of my ute 10 years ago still seriously outperform the supposedly "bigger and better" ones I recently put in my daily commuter wagon, even though they are mounted correctly and have a similar sized void behind them. Both are just driven directly from the head unit and both head units are rated at the same output/channel.

Cheers.