Hey Smoke, those are very realistic numbers to expect from the XV15, I had a pair of them in my 2800 cf LR and did achieve those results with a single 15, you may want to pick up a copy (CD) of Bass Mekanic-Quad Maximus, this CD will let you know what the XV15 is capable of, really heavy bass material (songs) along with sine sweeps, pink noise and 10Hz to 100 Hz test signals, if you pick up analog SPL meter (highly reco'd) you can measure the dBs at your listening position for the FR listed. I think the XV15 is really going to make you smile, I don't know how Tom and Jim can offer such high quality products for the asking price, 5 year bumper to bumper warranty, made in the USA and CS before and after the sale is exemplary. For me the PSA subs are lacking nothing in performance, well you will soon find out, congrats, and no I don't work for PSA. At least pick up a SPL meter so you can get the maximum clean output in the locations you decide on.
Amazon.com: Quad Maximus: Bass Mekanik: Music I think you can download a lot of this CD.
These are getting harder to find, the analog meters.
Amazon.com: RadioShack 7-range Analog Display Sound Level Meter: MP3 Players & Accessories
Good luck my friend and let us know what's up.
Cheers Jeff
Bass in the teens for me is like the sound concrete makes when it cracks and splits, pure adrenalin rush