High Sierra Topix

I have a yosemite wilderness permit for this August. The email I received back clearly states I must camp at LYV the first night which I will surely do. It lists my exit trailhead and exit date. I cannot see from the FAQ on the yosemite NP website if I am allowed to change my exit date on the fly. For instance, if I am having a great trip and want to stay another night or two, am I allowed? Must I exit at the trailhead listed on the permit?
Thanks for your response.

You are allowed to vary from your itinerary once you spend the first night in your designated camp area--and as long as you observe all other rules. But the Park Service is not interested in forcing you to hike faster, or slower, or stay exactly to your plan despite how you are feeling. You are free to alter your route once you get going.

Note that this doesn't include leaving the part via Donahue Pass unless you have a permit that allows you to do this. But if you decide to stay in the backcountry one more day, or one less, that's up to you.