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Why not simply get in contact with Robert at FP or do a search as this has been covered in nearly every FP Red thread created. I'm not being sarcastic but there are better ways going about getting the answer to your question.
Minimum rating of 57lbs/min, but has been estimated at flowing over 60lbs. based on power and fuel consumption. I don't think there has been a definitive thread on the max lbs/min. flow though.