Has anyone tried this out?

see www.wavescaraudio.com

They claim,

Lets 4"-6"door woofers sound like 8"-10" subwoofers
Lets a 8"-10" sub sound like a 15" subwoofer
Lets a 12"-15" sub sound like a set of competition subwoofers
Unlike bass boosts, does not increase peak power and speaker excursion