How did you measure the pressure? There is a crossover pipe before the mufflers so the pressure should always be about the same. I don't know the Trident mufflers or their internal configuration but if there is a big difference then I would think there is a blockage in one and/or a big leak in the other.

Also welcome to the forum.

Cheers, Richard
~~~~~~~~~~~~
09 America, Staintune Pipes, K&N, Breathe, Hagon Nitros, AI & O2 removed, tune 20184 (modified), MTX-L a/f gauge