3 ohm subwoofer and a dual 2 ohm?

it is model cft-15( if that helps)

and it is 17*17*12 3/4

yea i was thinking that...keep the 10" and sell the 15"

which do you think would be better for alittle more than SQ like a little more bass?

I just prefer quality products like JL and MTX for my subs thats all. Im guessing you think infinity is high quality door speakers too huh?

This is a myth and is completely incorrect.  There is nothing inherently more "sloppy" or "tight" that is created by cone size.  It's all in the enclosure.

Your enclosure is on the small size for a 15" woofer at 1.5 cuft.  It could be used, however, and will sound a little boomy with peaks up around 60Hz, but it'll be OK.  I'd recomend filling it with polyfill (stuff at least a pound in) and throw about 500 watts at your CFT-15.  HERE's the specs in case you don't have them.

With most manufactures they use the same motor for the 10" 12" and 15" on a woofer of the same series. That being said, the 10" will be more accurate than the 15" because there isnt as much surface area for error. In other words, the motor will push the 15" more unevenly than the 10". Or atleast this is what I have been told time and time again by numerous credible people.