Tuitavuki, McRoberts, Hastings Rugby and Sports lock Lucas Albornoz, MAC centre Mataeus Marsh and Central fullback Kodie Drury-Hawkins were the Saracens other tryscorers. Watson kicked four conversions and Napier Old Boys Marist first five-eighth Johnny Lauano six after taking the field as a substitute.
"We're pretty proud of the way the boys played. A lot of the boys didn't play last week and made a statement today so we're going to have some good headaches when it comes time to name our top side," Saracens head coach and former Magpies captain Mutu Ngarimu said.
"It's equally pleasing how well the boys have put aside their respective club allegiances and brought into the culture of this team. That is showing out on the field too," former Maori All Black Ngarimu added.
The Saracens will host the Whanganui Heartland side next weekend in Napier.