I can't help you on prices, but I just recently replaced my entire system due to theft, so I've done some shopping around and I can give you a few helpful (maybe) tips. If you just want a system that bumps nice, I'd go with the MTX and save some cash.
I owned 2 10" Thunder 6000 series, which are basically the equivalent of the 4500 series now (according to the MTX specs like xmax, wattage, and such). They sounded nice, and got loud when I needed them to. The sound quality was decent for the money. I'm sure the 5500s with the right amount of power will sound good too. With that said though, I own a JL 12W6v2, and if the W3v2 sounds half as good as the W6v2, I'd spend the extra money on the JLs!
I've used (and still use) MTX Thunder series amps. They are quite underrated and they sound great. My Thunder 502 is rated at 180x2 @ 2ohm and 12.5v, on the birth sheet: 214x2 at 2 ohm and 12.5v!! I'm using them to push JL Audio speakers, and though that may be heresy to some, I think it sounds awesome! And...Unless you're going to use all of the bells and whistles on the 500/1, I think you could save some cash here.
I'd also skip the Kenwood unless it's an Excelon, because other HUs at the same price points of the normal Kenwoods generally outperform them. Don't get me wrong, I've used Kenwood HUs for the past 8 years, but I know their basic line isn't the best out there for the money. The $250 price point Excelon is the KDC-x589. It's a nice unit, and has 24 bit Burr/Brown DACs for the CD section!! Crutchfield has free shipping on the x589 right now too!
I know Kenwood has a bad name among the MP3 and MSP crowd, but their new HUs are vastly improved. I've got the XXV-01D, and it's a beast!
You could also save $50 by going with the Alpine CDA-9847, which is basically the same as the 9851, but without the flip-down face. I definitely think the x589 has the $250 Alpine beat hands down though. Try this link:
clicky!!
Hopefully I haven't confused you!
