An interesting experiment. I suspect you will probably wind up disconnecting the mids, since they will overlap the woofer and tweeters and make the setup biased towards the midrange. Interesting to see (hear) what it sounds like. I suspect just the two speaker setup will sound better than the OEM.
Your original post indicated you did the direct replacement of the woofer and the tweeter, leaving the mid and using the original amp but you were disappointed with the bass cutoff. Did you check to see if your phasing was correct? Loss of bass is a classic out of phase symptom. I can't imagine the new speakers being not obviously better than the OEM.