I thought the shaker 500 was lacking also.
I had DLS 5x7's installed front and rear, and a soundstream 5 channel 800w amp. I love the sound very clear highs, lows, and mids. Originally the door subs were very muddy. They rewired the subs in series, which raised the impedance, and they are nice and tight now.
I have a convertible, so the rears are on the sides not in the rear deck, but I like the DLS speakers.
The whole thing installed with a Bass knob (which allows you to control the subs independantly) cost me $650. You should expect to pay a little more though, the place that installed for me, is a client of mine and I'm sure I got a break.