my brother is going to put a shortned ss borgwarner(sp?) in his ke20 with a 4age, soon to be a 4agte. He is going to get the diff ratio changed so it is about 4.1:1. I keept telling him to use a hilux diff but he wouldn't listern. The hilux diff already has the perfect diff ratio, and is near unbrakable.
A Hilux diff is massive overkill for a 1.6L NA engine. It's heavy and it drains a lot of power too. If you're staying NA a T series diff will probably be fine, otherwise an F diff would be my pick.