Frostiex, your Suzuki stock front and rear speakers are 6.5". If you are looking to upgrade your stock car speakers on a tight budget I highly recommend Infinity 62.7i Kappa series 2-way speakers $79.99 mated with a robust amplifier. As others recommended, focus on the "front stage" and use the stock speakers in the back for rear fill.http://www.millionbuy.com/inf627i.html.
As for an amplifier Powerbass ASA300.2 $79.99 delivers everything it claims and careful gain adjustment will yeild excellent results with the 2ohm Kappa's. This ampis 2ohm stable and will deliver 150w rms to each channel.http://www.millionbuy.com/powasa3002.html
If you are looking to go all out and spend big bucks look at JL Audio Evolution ZR series component speakers and the new G series amplifiers. Top notch stuff! I am currently running a/d/s 6.5 " comps in my front doors with the tweeters mounted in the dash powered by JL Audio 300/2, 15" SI Mag D2 sealed enclosure powered By a JL Audio 1000/1 and CDT 6x9's in the rear panels powered by JL Audio A2150. I stripped my car to bare metal and sound deadened the entire interior with Raamat. The sound is mind blowing!
demetman
