definately go with the 1 farad, its better to stockpile more charge on your cap so that its available when your subs need it, then to short them and start draing off the battery again. You'd be defeating the purpose and your lights would just dim again. think of the cap as a place for your battery to store extra power until its needed, like a tub of icecream with your bowl of icecream sitting in it. you eat your icecream from the bowl first until its empty, then you start eating from the tub

, mmmmmmm icecream!!!!