It actually depends on the stereo. Some double-dins can be fitted without any modification, others like mine (fh-p8000bt) required some fun with a dremal and a razor.
I circled the little lip on the bezel on the top that i had to dremal away, there is also a little lip on the bottom that i had to do. My suggestion is to see if it will slip in without any modification first, then move on to doing that.
Also I, believe this little lip needs to be removed via razor blade for any double din to fit.
Just cut it off slowly with a new, sharp razor. Don't do what i did and slip and slice the outside of the dash.
Another issue i encountered was the hazard light button would push down on the top of the receiver to fix that i just dremeled away a little bit of the bottom. There is quite a bit of plastic there.
Now the real challenge is getting those four bolts back in there, which i have not accomplished but the clips seem to hold my bezel on just fine.
I wish i had pics of when i did it, i could clearly show you and i don't really want to remove my stereo.
edit: also what kipp said. get the double-din kit.