Question about costume collection system

[Pekingduckman]

If I gained achievement bonuses from a set, then discard or mail one of the costumes, do I still keep the bonuses?

[Grimoir]

You should yes.

[Ryunosuke Takahashi]

Long as you claimed said bonus I don't see why not.

[Draknalor]

Don't see why you would discard something.. just put it in the showroom.

[oblo]

Can confirm this works, tried it last week by mailing the Blood Raid backpack from an alt that actually wears it to my main to collect the bonus and back.