I changed just my fog bulbs (to a bluer light to better match my headlights), but that's it. Unless you go with a full-on replacement of your housing (like from OSS) you will never see the level of light output the new F10/F30's have. In fact many of the plug-n-play bulbs look down right terrible esp during daylight hours. The Lux LED replacement bulbs are probably the next best thing although they will not match the light output of OSS.
There are LED fog light kits out there, but you need to buy a relay to avoid throwing codes.