Rule reminder
After a comparative expression, 'di quanto + subjunctive' introduces a clause of comparison. The tense of the subjunctive depends on the main clause tense: present main → present/imperfect subjunctive; past main → imperfect/pluperfect subjunctive. A pleonastic 'non' may optionally appear before the subjunctive.
Il viaggio è stato più stancante di quanto … (aspettarsi — noi).