Infinity Qa's with a Pioneer BOFU full-range...

[mikje]

Hopefully this doesn't sound crazy, but what the heck...
Any ideas on what I might expect if I replaced the woofers in a pair of Infinity Qa speakers with a pair of the Pioneer 8" full range speakers? The midrange on these Infinitys is really lacking and it seems the midrange would have to improve with the Pioneers.
Being that the speakers are listed as 4 ohm and the Pioneer is 8 ohm, is that an issue, considering that I'll only be using the tweeter.
I ran the Pioneer specs through Win ISD (I used the specs from MCM; they were more complete than what PE has). The Qa box size is almost perfect. (It's a sealed box.)
Now, what I don't know is how to read the graphs on WinISD. Is it something someone can, or would be willing to, explain in a paragraph or so?
Here are the specs for the Infinitys.
http://www.bobbyshred.com/images/Qa_Tech_Sheet.pdf

Thanks for any ideas or suggestions,
Mike