EV 150 - does it require a rudder reference?

Hi,
I am looking to replace my autopilot with an EV150. The pump sizing etc seems to be correct for my boat - 32' Luhrs convertible with twin 370 HP diesel straight drives. Steering is a Teleflex / Seastar BA135-7.

The system packs do not include a rudder reference. Does anyone have any experience running this size power boat without a rudder feedback?

thanks,
Mike