The Eagles are currently second in the Championship, three points behind leaders Cardiff, and Holloway feels a couple of additions in the New Year will help maintain their challenge at the top.
"I'm learning more about the team each day, and I know that to sustain this momentum we've got to get stronger," Holloway told the Croydon Guardian.
"I want to do everything I can to keep this momentum going forward and test everybody on that pitch.
"One or two of them are playing week in, week out and they have no pressure behind them.
"We have got that in certain areas but we haven't got it everywhere. I would like to add a bit of meat to that come January."