Hey steviep
As john has just said 5.25" or 13cm speakers will fit straight into both the front door cards and also the rear plastic boxes that sit on the parel tray.
I've just recently installed a new Headunit and also 4 speakers and a pair of tweeters and was in the same boat as you. "I didnt want to chop or alter anything"
The rear speakers sit ontop of these funny plastic surrounds there is only 1 bolt that holds them inplace so getting them out is easy, but separating the old speakers from the plastic boxes and mesh grille is rather tricky
I'll post some pics here soon