i was told a while ago that if you dont amp new speakers they can sometimes end up sounding worse than the stock speakers
i was thinking these 6.5s for the front
http://www.sonicelectronix.com/item_...TS-A1674R.html
and these 6x9's
Pioneer TS-A6964R (TSA6964R) 400W 6" x 9" 3-Way Car Speaker
if i go with an amp i was thinking this 2ch one
http://www.sonicelectronix.com/item_...-GM-5500T.html
or this 4ch one (more expensive)
Pioneer GM-6500F (GM6500F) 760W 4-Channel GM Car Amplifier
the two channel i would just wire the speakers so id halve the ohms and run off a 2 ohm load for each set of speakers