i just think that if anyone was to start upgrading spund gear, it should be: First get a nice headunit. Then splits. If money is a problem just run the splits of the head unit. a nice amp to go with the splits would be the next step. Finally, a nice BIG sub and amp to power it. A lot of poeple these days are saying to go all out on an awsome pair of front speakers and leave the back ones off. Honestly, does anyone really care about the passenger? subs in smaller cars ie. corolla.. we don't really need an awsome one, because the car is small we can get by with 300-400w rms. If people are looking to do their entire system at once, you can go for a 4 channel and power the whole car or the way i went through above (you can have alot more power that way) I'm not saying this is the way it HAS to be done. just that i think you'll probably get the most out of the speaker upgrades if you take it step by step.