I can get about 95dB out of it at 30Hz. It gets pretty noisy below that but still produces audible and feelable bass.
The only time I have had issue with it making too much noise is on movies where they use LFE to add drama and there is pretty much no other noise going on...you can hear the port there.
Other than that, it does quite an admirable job in a 17x13 room with a side opening to kitchen, another side opening to 2 story foyer and open to the hall in the back.
For our secondary HT, this system of 3 X-CS, 2 XL-S and 1 X sub has been pretty impressive.