Thanks for the posts.

If I don't have a subwoofer and no amp, but already have component speakers and tweeters at front...

Is there recommended speakers to replace my rear OEM ones to get better bass?

I'm not going SPL here (boom boom), but rather SQ that is within reasonable reach (ie. the rear door panels would not vibrate or sound crashy due to bass).  I never play loud, but I do appreciate fuller low frequencies which should be provided by the bass c/o subwoofers.  However I don't intend to spend on amp and subwoofer (that requires space) if possible.  Not really to save cost, but to maintain the stock look and space.

So I figured, maybe your recommended rear speakers can handle the bass, then tune to have the bass go out there?  Is this possible?  Sorry for the noobness, it was just an idea that went thru my noob ice head.