need speaker distortion solution

Currently Installed Sony CDX-GT200 Deck http://sm.crutchfield.com/S-fYXdiEMMdP7/App/Product/Item/Main.aspx?i=158GT200&tp=5685&tab=features_and_specs Alpine SPS-57C2 Front http://www.crutchfield.com/S-re0F43MfFOO/App/Product/Item/Main.aspx?g=51900&i=500SPS57C2&c=3&tp=93&tab=features_and_specs Pioneer TS-A6881R Back http://www.crutchfield.com/S-cIppmdHzCmm/App/Product/Item/Main.aspx?i=130TSA6881&tp=92&tab=features_and_specs I'm installing a MTX Thunderform behind the seats. I want more upfront bass but my main concern is distortion at high volumes. I'm going to RAAMmat & Ensolite both panels of the doors. Move my alpines to the back, they aren't the best but my back seats cover the rear speakers so you don't get much sound out of them anyways. But where to go from here is my problem. Should I get a nice set of coaxials or a decent set of components? Is the distortion coming from a cheap head unit or the speakers? If distortion is from lack of power, should I replace head unit or install amp? Any help you can offer would be greatly appreciated. This is a big purchase for me and I don't wanna love it up by getting the wrong stuff.

actually i took a look at the h/u and its not going to work with a mids and highs amp, because of only having 1 preout. what i would do is look around for a h/u that you like that has 3 preouts. this will give you the ability to add a mids/highs amp and then finally give you the sound your looking for.2007 Acura TSX

SQ setup in the works

The head unit will work just fine with a mids and high amp.  It just means he won't have control over individual volume levels between the fronts, rears, and sub.