alright... first off if your willing to spend the dough, get pioneer, id personally go for the option of 1 12" and a couple smaller ones so the 12" would handle the big noise (bass) and the smaller ones will handel all the small noise (clarification), also go with premium wireing, which is the gold plated wires that are used on the pioneer sound system in the pioneer car, if you supply your own wiring it brings the installation costs down, YOU NEED AN AMP!!! from my experiance the cheaper the amps are the longer they last (i know it soounds silly) it all depends on the wattage of the speakers, if you need to go into strathfeilds or repco or watever store you have and ask them to help you, get a few quotes, and compare prices, for front speakers deffinatly go for 9" i know its sounds peuny but they are the best for the front sound, also look into getting tweeters they are insane!! hope it helps and good luck!