The problem doesnt sit in the fact that its a 5.25" or 6.5" speaker... its the magnet structure. For some reason a 6.5" is alot bigger then a 5.25" and when you look, notice the big plasticy "boot" the speaker sits in? You should be able to get rid of this but on occasion water DOES get into your door, if you remove this to make the speaker fit make sure top the top upper surface of the round cutout on the door you put something to protect the speaker from moisture...
