First I'd make sure it's being evenly distributed from left to right when wound. If not, that'll cause high spots and pillar rub.
If it were me, I'd remove some of the backing so long as there is sufficient backing left. Think of it this way, fly lines cost a lot more per foot than backing and backing is lot easier to splice together than fly line. If you err, do so with the backing.
I haven't a clue who made the line that came with the outfit.