I third the above. Twenty degrees at least. For my oven (which is ff), I sometimes find I have to drop the temp by up to forty degrees. When I last made muffins, I dropped the temp in the recipe by twenty, but found I had to go lower again, and wait for the oven to cool down a little before putting in the next tray, and also change the baking time. My oven just seems to be uber hot, but maybe I still have to get used to the fact that its just ff.

Generally recipes (if they give you different oven type temps) will say the ff is twenty degrees below the norm. Its a matter of keeping an eye on what's in there, and going accordingly. I always note down the temp and time that works for a particular recipe, in case I make it again. For example, the roast chicken in a bag that I did the other night, the recipe specified to cook for two to three hours at one seventy. So, my oven immediately on one fifty, but even two hours could have been just a tad long cooking time, even though it was a pretty big chook, so I noted this down when I wrote out the recipe for myself.

Good luck.