Get some serious amplification, and flip polarities on ONE midrange, and ONE midrange only. (I use passenger side)
Yes, listen to it out of phase, it may restore bottom end.
Buy a brand name amp. Alpine, soundstream (they are all very similar, just physical differences) or a Fosgate.
Worse comes to worst- slam a 10" tube in the trunk. Use a 4 channel to run everything.... Placement of amp? Somewhere along left or RH side of trunk.
Amazon.com: Bazooka BT1014 10-Inch 4-Ohm Bass Tube: Car Electronics
PS- the old soundstream amps sound great, but they aren't real reliable nor are they good at noise rejection. I used to sell them, and at one time had the MC300, MC140 and D60II in my car. What a pain in the ass to keep the system quiet. Be careful with them
If it wasn't for the fact they were cheap I wouldn't have run them. WIth that being said I'm about to slam a reference 405 and a 15" and separates in my new BMW...