Perfect Speed- If you're not using 4" pads, I'd recommend that you get some.
M105 is good stuff, but sometimes you need to use it with very aggressive pads.
I never had to do serious correction on my C5, but on very hard clear I *have* had to resort to 4" *wool* pads on the PC (with
M105). LC's PFW pads are the usual choice, but I've also used the 4" yellow wool pads sold by
Cyclo Toolmakers, which are made by Edge.
Note that those will leave some not-so-micro marring of their own, but the
M105/4" yellow wool combo is probably about as aggressive as I'd recommend. Anything so bad that *that* won't handle it, I'd rather wetsand with 3-4000 grit and then polish out the wetsanding marks (which can be a lot easier and safer than one might think, compared to being very aggressive with a polisher).
Oh, and even with the PC/4" yellow wool/M105, I had to do many passes to accomplish what I was after. Don't expect just four or five tries with *any* PC-based combo to be sufficient if you're doing really serious correction.