2.75" piping is the optimal size diameter pipe.
Going to 3" won't really hurt.
The point of the 2.75" pipe is that the TB is the same size so the airflow doesn't have to change pressure.
I would try to find a 2.75" to 3" 90 degree coupler to connect the TB to your piping.
Using a 3" coupler will cause turbulence at the TB.
