You basically can't upgrade them to Lv40.Originally Posted by On3EyeJim Go to original post
You can upgrad them to 515 which is a little stronger than the Lv30 but that's max for now.
If you want to get a Lv40 exotic, you basically have to farm for it again...which is quite a pain.
The upside is that the exotics have been nerfed quite a bit, so they aren't that powerful (or to put it bluntly there are many ordinary weapons that are stronger),
so unless you really like a specific exotic, it's probably easier to just play the game and without thinking too much about them and hope that an exotic will drop while you're playing.
Don't throw away your old exotics apparently Massive did say they might allow exotic upgrades to 40 later on.
(But it was a "maaayybe" so keep your fingers crossed about it.)