I recently bought a vita on ebay that is on 3.60 but there is a lot of personal data on there.
So can i perform a factory reset without updating ?
Or will it prompt me to update ?
You can do a factory reset without updating. To be safe, keep the Vita in Airplane mode before you do it, and then when prompted to connect to wifi on first time setup choose not to. Then connect, install Henkaku, and you should be good.