I have two 12's in my trunk and had some old factory speakers on my rear deck and some MTX speakers on the front kick panels. They have all blown so I replaced them all yesterday with four Alpine SPS-13C2. Im not sure what specs might help yal help me but the RMS on the speakers is 35w, with a peak at 175. Now I'm not sure of any specs on my old speakers because I couldnt tell what exact kind they were. Should I install a bass blocker to prevent them from blowing?
Also, Im looking for new grills for all of them so If somebody could point me in the right direction (a good site to order from) that would be great.
Chances are they blew becuase they were cranked up too loud. Your new speakers will take a bit more of a beating without failing but if you want to be sure and have better sound you'd be best served amping your speakers, or at least the fronts with a decent 2 or 4 channell amp that'll push at least 50W or so RMS to each speaker.
Also, I don't know what you're running for a head unit but if it's aftermarket definately adjust your crossovers so that your speakers are just working to reproduce the highs and mids, like Abe suggested. If you have a factory deck then bass blockers might help some but you'd be best served moving to an aftermarket deck, again for better sound and more adjustability.
I don't' know if you're looking for Alpine grills or generic, but keep an eye on ebay for both. You can probably also get them direct from alpine but you'll pay a premium.