Last year I started to do 10 miles out and back time trials with a local group comprised of mostly triathletes. At first, they were all smoking me, barely able to do 22 mph. Slowly but surely I got faster. Last weekend I averaged (according to my Garmin) 24.2mph (24:49) lately I have been finishing in the top 3 over all.

I am using my road bike for this. I have aero wheels 50mm, aero bars, 5000strs, aero helmet,

My goal this year is to cross 25mph. But it seems like a massive gulf to pass. Any general tips?
Where am I going to find 49 seconds from???