Swapping 4 piston Brembos on my Cali 1100 using Guzzipower 65mm adapters ( Thanks Ed!) and so far the only additional mod needed seems to be the re-position of the angle of the rear brace (on the front fender) to allow for the 4P calipers to clear. Thought about using the Cal 3 fender brace which has a bit of an arc, but I am not sure it would help. Pics will be upcoming as I make a bit more progress. For the snapping suspender types who love their P08 calipers they can go on and enjoy them, however, my old Cali EV with 4P calipers was a better stopper than this carbie 1100 so that is the criteria for the mod. Of course this falls in the category of why does a dog licks its b**ls, but If anyone has done it and has other nuggets of wisdom, please feel free to chime in. Cheers