I have searched high and low in this forum and cannot find anything about the results of replacing the factory 6" subs behind the seat (preferably in a Roadster). I have read about boxes in the trunk but I am not really interested in this solution.

I replaced the head Unit with a high end JVC KD LXH550 and the stereo sounds 10 times better. But I want to add Bass Blockers to my front speakers and am afraid I will loose all my bass because the back subs are pretty much useless. Is it the size of the stock subs that make them useless, the quality or the power? I know it is probably all three of these things that are the cause but if I just replaced them with something high end would they sound the same?

Any thoughts or solutions are welcome.