You can make baffles in the shape of a 6x8 cutout to fit the mid and tweeter in the stock 6x8 location if that bothers you.
As it stands right now, I am about to use some of my installer abs to make plates to install tweeters in my 2006 GTs 6x8 location.
Also, since you have the convertible, please take note of the power handling on JL Audio's Stealthbox. The model for the vert only handles 500 watts RMS due to the fact that the subwoofer is in a slightly smaller enclosure than optimal to make room for your top to go down in the trunk. Granted, you can run the JL 750/1 but you will have to turn your gain down a bit to ensure that the subwoofer will never see more than 500 watts RMS for an extended period of time. Also, if you manage to turn your subwoofer inside out, JL Audio may not warranty it if you say you were powering it with a HD 750/1.
You could also do something like this if you were willing to relocate your factory mirror controller (and provided you are good with fiberglass):
http://i474.photobucket.com/albums/r...0068_large.jpg
Again, not mine, but you would have to obtain some replacement mirror covers (sail panels) and construct some pods out of fiberglass. You can use your own, but it will cost you more $$ to return your car to stock if you ever have to.