Rewiring stock amps to new head unit?
Ok so I am a bass person, but lack the speaker knowledge. I need my car to not have serious mechanical issues at this time, thus why I have not further modified with the exceptions of exhaust and intake. I have a 2002 V6 convertible with the mach system. I replaced the head unit and also had a custom box built for 1 12" sub and amp. The interior speakers however suffered and are now complete **** so I want to know if anyone has rewired their stock amps to a new head unit? Also I want to know what size speakers I have before I remove the door panals to replace? I think they are 5x7, but not sure, I went to crutchfield and they gave me like 2-3 different sizes so??? Any help would be great thanks?