did you mig them? the remainder of the welds still stand out a bit, my eye was drawn to them first, although I appreciate it is difficult to get into the tight corners to grind them out
as for restriction, hard to say without either seeing the original oem manifolds to compare them, although the bends are quite long so it shouldn't be too restrictive.
what engine are they for? yank import v8 or something more European?
places like the collector it is impossible to get a dremel, die grinder, file etc in to grind them out...
weld them neatly so you don't need to grind them afterwards
easier said than done for many of us, myself included
ah the good ol' rover v8. one of my favourite engines as it happens.