you don't know the service history of the motor prior to when you got it.
i would be requesting toyota to be using a good oil, i like the HPR 10 or HPR 15, and going with the garrett turbo. by rights, nothing should go wrong, and if it does, well f@$k hey. its unlikely to do it within 9 months, so you may aswell throw the warranty away.
sure you can't take the toyota payout get a second hand replacement, put that on, thus keeping it stock, thus keeping it within warranty, so if it does go bang, u still ahve warranty and you have money in your pocket?