I don't think there's any chance of fitting it without removing the map pocket. The only thing i can really think of, is maybe cutting the map pocket a little and turning part of it into a speaker pod with some crafty fibreglass work. (If you understand what i mean..)
You may be able to do it yourself if you're handy with fibreglass... otherwise you could get some professional ones made up for probably around $200 to $300.
I think it cost me around $100 overall, for all the materials to make my own.