I usually adjust the endpoints on each elevator servo in the transmitter so that they are even at center and max throw both up and down. This is assuming that you have a computer Tx and are plugging each servo into a separate channel, not using a Y harness.

I just got my Extra 330 this past weekend and haven't started on it yet BUT,,, man-o-man, this thing is light!! Unless it has some weird flying traits, I'm gonna love it!