Mr. Legend, I've got to admit being the legend that you are...I"ve never heard of you.... anways..
Give ppl more time than 10 minutes to respond. most ppl are at lunch or working right now... If you're after just a little more bass (and I emphasize lITTLE) you can replace those with subs. I would only replace one and put a quality speaker in the other whole. With only one sub, you'll double the air space but that still doesnt' solve the functionality of the sub You're not going to get any kind of bass out of the center area, especially in an RT. Bass is non directional and needs to bounce of surfaces to even remotly sound halfway decent. Years ago I put an 8" sub in a box snugged against the footwell area of the passenger, left plenty of room and it had good bass. With the hardtop on, it sounded pretty good. With the top off it just sound ...ok...
I know someone and see a certain RT/10 ALL the time here in FL where he put 2 12" woofers in his RT/10 in his trunk and probably spent close to 10k in his system. The bass was almost non existent. He even had the bass somehow funneled thru the 2 holes in the center console so as to sound just like 2 10's in the car. Point is, your not going to get bass in a convertable...... at least not what I call bass. /images/graemlins/supergrin.gif
hope that helped...
Gerald