as far as amps go that depends on the woofers. as for an amp for the high the pdx 4.150 is a good amp and it really small. and if your not pushing more than a 1000watts rms the pdx 1.1000 for the subs is also a great amp and its stackable with the pdx 4.150. Front and rear speaker is your on a budget the alpine R types are good, if you have a few more bucks to spend the the X types are a go. Subwoofers that are low wattage and really good in sound quality are a brand called treo, my little brother has 1 in is Z and its as loud as my jl w7 and he is using a crappy amp with it. a head unit . . depends on what you want. navi, movie capabilities, bluetooth and so on. single din double din.
