The 26-year-old believes the Baggies’ rise in status in the top flight can be attributed to their efforts at the back but he insists the club can still improve.
West Brom conceded 52 goals last season and are on track to better that record, which currently stands at 43, with six Premier League games remaining.
"If we can beat last season’s record of goals conceded that will help us to stay where we are,” Mulumbu told the club’s official website.
|13/1||West Brom are 13/1 with BetVictor to beat Newcastle 2-0 on Saturday|
"Every year we have stepped it up and improved – and hopefully the statistics can show that as well.
"It is another challenge to keep us motivated. We don’t want to let this season finish on a low and be in the middle of the table. We’ll keep aiming high. In this league it is important to be strong."
Mulumbu maintains West Brom have replicated the defensive rigidity displayed by the likes of Manchester United this season and has pointed to the form of goalkeeper Ben Foster and centre-back duo Jonas Olsson and Gareth McAuley as reasons for the club's improvement.
"When you see a team like Manchester United, sometimes they don’t really play well – but defensively they are really strong and you cannot score against them.
"We have shown more signs of being like that this season and we need to keep building on the players at the back like Ben Foster, Jonas and Gareth."