I own a 1998 Jeep Cherokee Classic and I am planning to replace the stock speakers with new ones. The trouble is, I don't know much about speakers. The car has 4 5.25" speakers and an aftermarket head unit (Aiwa CDC R227) with a power output of 180W (45w x 4), which I plan on keeping. My questions are: (1) What brand(s) of speakers would you recommend for overall sound quality (especially bass)?, (2) Do I need to run an amplifier to power the new speakers?, and (3) Would a component speaker system require an amplifier?

I am planning on spending $200-250 to upgrade the speakers. Any suggestions and help would really be appreciated! Thanks.