You can use the diyma vBulletin search at the top of the page or use Google advanced search. I prefer Google advanced search. The picture below shows the way to format your query into Google. First type site:diymobileaudio.com , then type the keywords you are searching for, that easy. Be specific, think about all the words you could try that relate to your research and you will likely find many threads to help you.
For instance, "what size speaker wire should I use".