As fast as I can runoff from the MLT with the valve full open, which is about 3 quarts per minute for a typical grainbill. My MLT has a copper manifold, there are pics of it in my user gallery if you poke around. The braid in the kettle is just to keep any loose hops etc. that make it beyond my hop bag from clogging the pump.
Mine is about the same. Remember that the MLT -> BK runoff is gravity-fed and the pump outlet valve is partially closed to equalize flowrates.
If you think you may get stuck, use some rice hulls. The MLT braid works great for me though.