Ok guys, I'm trying to help a buddy put together a HT system on the cheap. He bought the Audiosource SW15 after hearing my SVS 16-46pci. He wanted deeper lows that he can feel. However, it seems to rumble more than produce bass that's felt. So we've determined that the stock speaker is the weakest link. Therefore, we are now in search of a good inexpensive replacement to produce better bass. Any suggestions for preferably around 100 or less? BTW what are your thought about using a 15" car sub from say JBL, MTX etc?