for the best sound quality, you want to keep the tweeters as close to the midrange as possible. This will keep you ears from hearing the seperation of the tweeter and mid. I mounted my tweeter right in front of the midrange driver to keep them close. Just use some creativity and you'll be able to figure out how to do it.

Yes you need the x-over. Tweeters can't handle frequencies much lower than 2000 Hz. The cross over will keep the lower bass frequencies from getting to your tweets and blowing them. The stock tweeters are a lot different than yours. You will need to run new wires from your cross-overs to the new speakers.

Mish