Again, I dont mean to hassle you, but typing correctly and using some form of punctuation really helps understand what you are trying to say...
But the LPF is hardly the height of your worries. If you want to properly set your amplifier then do not expect more output than it was designed to do. And the LPF does not have to be at a certain point, but around 60Hz is a common selection for it, again this is just somewhere to aim and should be set to fit your taste of what tones you want your sub drivers to play.
And by the way, this 'spkrman told me to do....' crap isnt going to fly for long. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif