I think the hard core streamer folks (me, too) fish with a Rio density-compensated 200 grain line on a 6 weight with a rather short (4 feet), stout (0-2X) leader. It sometimes pays to have a heavier line (I have a T-300) as well. On a 4 weight, you can use a weighted leader and cast smaller streamers (bucktails), but this may not be as effective.