If you want to spend the money, you can definitely get stronger brakes.
At a minimum I would have the brake fluid flushed.
Someone will be along to tell you the brakes stop the truck and the trailer brakes stop the trailer. According to GM that is not the case. The brakes on the truck are part of the whole stopping package and have a dramatic impact on stopping the trailer.
Frankly, when an emergency arises you wont care what brakes are doing what. You only care that the whole package stopped you before you hit that heard of elk (my case) or what ever.
I have kept mostly stock parts with Bosch rotors and Hawk brake pads. They have a better bite that stock compounds. They also cost more than stock stuff but your getting a better product.