"He was born and raised here, and spent the first 18 or 19 years of his life here," Mrs Cossey said.
Mrs Cossey said the visit to Whanganui was possible thanks to a very short break in filming The Block NZ. The pair will only be able to stay in Whanganui for a few hours.
"When he first told me he was going to be on The Block I thought, 'Oh my god!' But I wasn't really surprised. He's a real go-getter - when he wants something he gets it."
Mrs Cossey said she had watched every episode of the show, recording them if she was unable to watch them live. She said was "very proud of the boys", who became friends when they met at a gym in Queenstown.
"They're really doing their own thing, and not allowing themselves to be too influenced by the judges."
Mrs Cossey is a member of the Wanganui Cosmopolitan Club and she said the club had been very supportive of Dyls and Dylz.
"They've put up posters encouraging people to vote for them for the People's Choice award."
Mrs Cossey said Big Dyls was well-known among regulars at the Cosmopolitan Club. He has even played Santa Claus several times at Christmas parties.
The Block NZ is currently screening on TV3 on Sunday at 7pm and Monday, Tuesday and Wednesday at 7.30pm.