i know some of you have put 6.5" speakers in your doors instead of factory size. i found a pair of alpine sps-600 for sale locally really cheap. i know they are discontinued but should i pick them up. think it will sound good in my doors or should i buy something newer?

 

You can make anything of decent quality sound good if you install/aim them properly, treat the door/surroundings, and provide ample power. Without doing those things, choosing speaker A over speaker B isn't going to make a huge difference.