RUGBY LEAGUE: The Western Mustangs could not back up their Mal Meninga Cup grand final triumph with a win in the National Under 18 Final against Parramatta in Sydney.

The Eels were out of the blocks early and built a handy lead before running out 48-12 victors over the Mustangs at Belmore Oval on Saturday.

Parramatta scored in just the second minute and didn't surrender momentum, holding a 28-0 lead at half-time.

That advantage got out to 38-0 after 45 minutes but the Mustangs kept working hard.

They were eventually rewarded with a try to fullback Denzel Burns before former Warwick player and hooker Zac Stevens also crossed for a second half try.

"We probably didn't start that well," Mustangs under 18s coach Eugene Seddon said.

"They were out of the blocks and we were probably 20 per cent off.

"We were pretty much behind the eight-ball from the kick-off."

The National Under 18 Final result didn't go the way the Mustangs wanted but the talented crop of youngsters still had an outstanding season winning the club's first Mal Meninga Cup crown in what was a tough 16-team Queensland competition.

"We just wanted to be competitive at the start of the year and we ended up being the best in Queensland and second in Australia. It was a very successful year," Seddon said.

Stevens, Warwick High student Cruise Martin-Brown and Assumption student Tino Stowers were part of the Mustangs team which played in the national final at one of the most famous grounds in Australia at Belmore on Saturday morning.

Martin-Brown will be back in Cowboys colours for this weekend's under-18 TRL footy.