advertised atm in straithfields new catalogue is a kenwood audio pack consisting of a 200w head unit 2x4" 120W speakers 2x6" 180W speakers 1600w boss amp and 1000W 12" sub in box for $599
id get that man you could get better bass with 6" but you have a sub so i doubt it will be an issue.but see if you can slip a 50 and get them to swap the 4" for the 6".because bigger is better lol.
how many rca's have the cd player got. i use 4" in my car n sounds good wen i listen to techno rnb n stuufff doesnt distort or anything and i turn it fulll blast most the time and its not running through an amp the 4". hope that helps