i did some google search and stumble on the ICE diagram audio setup. i am interest in the first diagram with a single 4-channel amp "http://cdn-static.lowyat.net/uploads/attach-40/post-11240-1158686129.jpg". i have an existing 4-channel amp with 70rms per channel. 2 pairs of the same 2-way speakers in the front and the rear. i am fine with the sound but it lacks bass. i am not interested in boxed sub in the trunk or beefed up system. i not looking for crazy bass where you hear the car next to you at the stop light. i was looking into two budget 6.5" drop-in woofers with frequency range of 60hz - 3300hz with Qts 0.58. i was wondering if a pair of woofers will produce weak bass like a pair of 2-way speakers that has frequency range of 58hz - 16k hz. i appreciate any opinion. thanks.

Mini Sub from RS Audio should meet your requirement," RS Pro S 165"...

i dun think u can achieve without any box for ur sub woofer. Eventho u install a 3 way front component speakers also cant get the frequencies from 60hz and below....

Please dun misunderstand SQ, we tune our sub not as loud as what u think, our mid woofer playing all the major role and sub is just to fill in.