You can add your subs and not have to change anything else about your stereo system. I've seen many guys on this forum do it so it can be done. All your parts look good as long as the speakers will fit in the slots already made in the box and if the box will fit securly in your trunk. Measure the diminsions of your trunk to make sure. If it doesn't or you don't think it will i would either look into making one yourself or find one that better fits it. You will also need the right cables to connect your speakers to your amp and xovers and caps as badass4.6 stated to connect your amp and speakers to the rest of your stereo system. If you know of a Moblie One or place like it in your area that does installations at a resonable price then i would have them install it, as long as it isn't a ghetto shop. I know Mobile One advertises installations for 1 dollar. If you do go to a store like that try and both buy the stuff you want from them and have them install it. Just don't let the salesman try and sell you something you don't want

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About Alpine
They're a good company and if YOU like the way those speakers sound then you should get them. As they say, "You get what you pay for"; so if its a well known name and the price tag is resonable then you should get a good product. Sound is all relative. So if the speaker sounds relativly good to you then you should get it. However, I am one too shop around

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