Several different pads, but all in the 5.5" range. Like it has been said anything bigger is going to bog down the machine and make it take longer to get correction if you can get it at all. I'm still kinda blown away that they even offer a kit for the PC with anything but 5.5" pads, but whatever. Heres what I would recomend.
For the heaviest cutting and correction you can get on a PC use M105 with Surbuf pads. These pads have great cutting power, are cheap, and most of the times the haze left behind can easily be cleaned up in one step with something like M205.
For good cutting, without leaving a ton of haze you can use M105 with either LC Orange Pads or Lc Hydrotech Cyan pads. The Cyan tend to finish down better but their downfall is their durability. It is well within the realm of posibility for a hydrotech pad to only last one or two uses, especially if you are using it on a PC with lots of pressure.
As for M205 you have a wide range of pads to use. You can still get good cut out of the M205 with a white LC polishing pad and it will finish down fairly well. You can also use it with the LC Hydrotech Tangerine pad, but again I have found the durability of these pads to be somewhat of an issue, however they WORK, so I will continue to use them.
You could also use M205 with a pad with no cut to get great finishing results.
They are GREAT pads....for a rotary. The only problem with the Megs pads is as far as I know you can't only get them in 4, 6.5, 7, and 8.5 sizes. That means there is not a god size pad to use on a PC. Sure you could do a whole vehicle with 4" pads, but it would take quite a long time.