I need to know what the stock size the door speaker is in my 1995 civic HB cx, and can I have a bigger size of speaker installed with little trouble???

I've got Pioneer 6½"s in mine. They went in with no problem at all.

i have a 92 same model. i was told by a local audio shop 6.5" can fit with a little modifying to the brackets. and then 5.25" for the rear sides and 6x9s on the cargo cover (if you have it.)