According to the marketing of them, yes. But in fact they probably do nothing to help and may just be one more drain on your electrical. There are tons of threads here discussing caps. You may want to spend some time reading them and decide for yourself.what's wrong with the cap? doesn't it help when the bass hits hard?
Oh, and where can I get wire for the big 3 and how thick does it need to be?
The biggest you can find is best... But anything bigger than stock is better than stock... I would recommend 0 gauge... as it is easy to use and is beefy.I here welding wire is really good for the big 3 and ground as well...