I have used Polk speakers in many of my cars. The shallow depth and scattered mounting holes made the install less difficult. Although no install in an '02 BMW 330xi is easy. Comparing these to stock speakers is not fair, so I won't. The bass is rich and not punchy. Midrange is well ballanced. The hi's are crisp and not brassy. I would like to have a little more power handling, but for the price it's just right.
Other components:
Eclipse AVN 6600 with ipod & Sirius
Hifonics Zeus ZXi8006
Polk MM651 (Rear)
Polk Momo 2104 Sub