replacement brake booster weaker than stock?

I got a leak in the brake booster a few weeks ago. It kept the system down to 15" vacuum. When I replaced it the vacuum shot back up to 25" so all is good there.
I replaced the lines from the master cyl to the frame and bled the system. Everything works great except it takes more pedal force to come to a stop than it did before. Which makes me wonder if there are different versions of that brake booster and they gave me one from a lighter vehicle? Or if theres something I missed in the install?
Any ideas? Brakes on these trucks are scary enough already. :bang

before you put the pump in did ypu pump it befor ypu but it on the new booster? you shove something flat in the end and fill it with brake fluid and then you pump manually it helps the bleeding procsess