Liverpool is the largest Cathedral in the UK (in sq metres), and the 5th largest in the world.
It's under-tower vault is the highest in the world
It's bells are the highest and heaviest peal in the world
There are two pipe organs in Liverpool Cathedral. The Grand Organ is the largest in the UK and is considered to be one of the largest operational church organs in the world with 10,267 pipes.
The Cathedral is considered to have 2 out of 3 of the most powerful stops in the world. The Trompette Millitaire and the Tuba Magna on the Great Organ operate on 50” of wind pressure and are each as loud as an entire organ played on their own. The sound of the stops is aided by generous 8-9 second reverberation in the Cathedral (source – Wikipedia)

Statistics:

Length:188.7 m (619 ft)
Area:9,687.4 sq. m (104,275 sq. ft)
Choir Vault35.3 m (116 ft)
Nave vault:36.5 m (120 ft)
Height of Tower:100.8 m (331 ft)
Under Tower Vault:53.3 m (175 ft)
Tower Arches:32.6 m (107 ft)
Bells: (height above ground) 67.0 m (219 ft)
         (weight) 31.5 tonnes (31 tons)