From another resource:
So I finally had the chance today to give this a try on my 07, apologies to the people who were awaiting more info. No, it is not a direct bolt-on. But yes, it could be made to work with not much fuss I think. The main issue as has been mentioned, is that the spacing inside to outside is not quite correct when putting these calipers over the S197 rotors. I didn't even try the S550 rotors because of the large difference in hat offset as previously noted.
So when I first tried the caliper on, and tried to slip the pads in, the outside was definitely tighter than the inside, so the caliper needs to move outboard slightly.
Then I tried it again with some generic 9/16" ID washers that I had grabbed out of the bulk hardware bin at work, seemed to put it in almost exactly the right spot.
Note that I did not try this with the backing shims that come with the OEM pads, just slipped the pads themselves roughly in to place.
Other fit issue is that the flex hose banjo block on the 13-14 GT-500 hose will have to be trimmed a bit, and / or the the caliper modded, for the hose to be able to sit flat on the casting.
Side view in place:
Washers that ware tried, sorry I didn't have a measuring caliper nearby to get an exact dimension.
As they sit on the caliper, they happened to fit perfectly in the machined recesses of the mounting bosses.
What they look like without the washers:
I then tried bolting my 18 x 9.5" Steeda wheel back on, they clear the Brembos with this much room:
When I snugged it down, the wheel would not spin. So there was some contact against the caliper casting. Unfortunately I couldn't put my hands on some of the thin wheel spacers that I thought were kicking around the shop, but by my estimation it would need maybe an 1/8" to 3/16" spacer to clear safely with that particular wheel anyway.
Bottom line, if these calipers do stay reasonably priced as they are now, for some people looking at doing a big brake upgrade this is an alternative to the Brembos to save some $$. My suggestion for someone trying do accomplish this, would be to get all the pieces together then take some more precise measurements to get properly sized washers or machined spacers made up. Other than that, just keep an eye out for a deal on a good used set of Brembos ...
cheers
Ed