speakers dont fit exactly, 03 corolla

I have a 2003 Toyota Corolla that I'm looking to upgrade the audio in. When I use the online "vehicle fit" guides, where you enter in the type of car you have an it tells you what speakers fit where. I tells me that I can fit 6 1/2in in the front doors and 6x9 in the rear deck, but it also says that they don't fit exactly and that I need brackets or to drill new holes of some sort. So the question is, how do I find out exactly what I need to do/get? And where could I get these brackets if I needed them? Thanks in advance. btw, its currently a stock 6-speaker setup. Some vehicle guides ask for that.

You need the custom it doesn't exactly fit guide......also known as take apart the vehicle and find out what you have to work with. Most shops either stock or will make the adaptor plates needed for newer vehicles. What is starting to become more common these days are speakers that are made into the mount and then the whole thing is riveted to the door. Will yoour vehicle have this in the front doors, chances are yes. That is when a custom job at a shop needs to be done.Top Secret, I can tell you but then my wife will kill me.

Where would I be able to get the brackets if thats what I needed? I know crutchfield says they include brackets that you need when you buy from them, but what If I dont want to get the speakers from them?

I was going to suggest you make brackets yourself, but then I thought if you were resourceful enough to do that you would likewise be resourceful enough to google speaker adapters.Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.