Udoh netted 16 goals for Town last season whilst also earning praise for his work rate and all-round game.
That form has lead to speculation he could leave Montgomery Waters Meadow this summer with Championship outfit Millwall reportedly keen.
Barnett, who now plays for Solihull Moors, first got to know Udoh during a loan spell with AFC Telford United back in the 2018/19 season.
The duo then continued their friendship when Udoh left the Bucks for Salop.
And the winger, who is from Dothill in Telford, believes Udoh has now transformed himself into a striker who can be 'unstoppable.'
"To be honest I'm not surprised at the success he's had," Barnett said.
"I've played with Dan at Telford and Shrewsbury and I know how hard he works.
"Me and him have done the off-season running together for the last two years and I've not met a harder-working striker that Dan Udoh.
"I know what quality he's got as well and he's moulded those two together. I'm really not surprised with the season he's had.
"If you look at his season for Telford he scored 28, which got him the move.
"At Shrewsbury he'd nip in with a few in the first couple of seasons but now it's like he's brought it all together.
"His hard work, with an ability to score goals, has come together this season and he's been unstoppable."
Barnett was released from Shrewsbury by Steve Cotterill last year.
But he has no hard feelings towards the Town boss and instead is focusing on being the best player he can be.
"I was there at Shrewsbury for 13 years and I'm the player I am today because of it and the coaches I've had," he continued.
"In the 2020/21 season, the first six months under Sam (former boss Sam Ricketts), I felt I finally found my feet and started to adapt to League One, playing in all the cup competitions.
"I'd say the only disappointing thing of playing in that period was not playing in front of any fans because of Covid, for my mum and dad not able to see their son make his full debut.
"Steve came in and had a job to do to get us out a sticky situation and fair enough he was getting the results. As a player you can't really complain about that.
"Football's about opinions and he had the opinion I wasn't right for the club and I completely understand that.
"I've moved on to Solihull and I'm just trying to prove I can be the player I want to be."