you just confused me, are you upgrading to components, If so most component sets come with Crossovers. Or are you going to buy a set of Mid range drivers and a set of tweeters, and do a kind of custom component set. And as stated most amps have internal crossovers, so all you have to do is set the crossovers on the amp and then you subs are fine. Or if you have a higher end Head Unint (I have an Alpine CDA 9853, with a built in 3-way cross over) with a built in cross over, you can set the amps crossovers to full pass/off, and you can run the crossovers in you HU that way you can adjust them better. But crossovers are needed