When I was going over my TC5 I bought used I decided to change the shock oil and opted to use the Losi 57 pistons. They fit great and worked just as well for me. They fit nice in the shock body so you don't get much if any blow by. My suspension was very smooth for me on a medium rough track with 35wt oil. Very happy with the results.
I do use green slime on my o rings to help with the seal. Has always worked well for me.