If you have the GXV160, I think it is there, but you have to buy the whole guard and redirect together. The diagram here for the 140 does not have a part number shown, but the 160 diagram shows “330H-0340 General Equipment GUARD, MUFFLER (MODIFIED)”. I think “Modified” means the redirect, because the main honda page for the 160 does not have it on there. I just happened to be looking for it, because one of ours keeps losing rivets and rattling like crazy.
It’s like $65 though, so if it were me, I’d be tempted to fabricate one for the fun of it…lol