While I also would like those pipes, I don't think you can add and remove mods from FTB like you want. Kind of the deal with FTB (as I understand it) is that it comes with certain mods that are confirmed to work together. Hopefully they'll add AdditionalPipes to FTB sometime in the future.
EVE Online characters:
Daedalus II ex-CEO TOGOA, Daedalus III slave of Daedalus II
Little Molok Asura Engineer
"Each day I don't get an attempt on my life by a robot from the future I see as a personal failure"