Edwin,
I really like the shape, the wood is beautiful, and even though I tend to get ever-so-slightly nervous when I see a fish in this particular shape, it's a great story and a beautiful inlay - love the shell, and the bass clef.
Now then, according to a very well-informed source, the custom bass-boost controls give you up to 15 dB increase! (and they weren't easy to build).
Are these standard shelving-type controls, and if so at what frequency do they start?
I have a hard time imagining adding that much bass, and suspect you might be reducing it elsewhere in the chain - you can't cut it with the low pass filters in the bass, but maybe in an SF-2 or a preamp?
Could you say a little more about how you are shaping the frequency response?
-Bob