We do too, we always have run split compounds and master sizes using both Carbotech and hawk, but my understanding was to use same master sizes and same compound for rear biased cars with downforce. I hope I'm not wrong, but Im sure I will know after the first lockupI have lots of years running on Carbotech pads, what I find is that a car that is weighted in the heavy in rear needs more aggressive pads in front to avoid the rear from locking up, I would far rather have the front lock than the rear, so I find this split of pad compound to be just about right, so I will see how this works out on the 818. The front and rear pads are the same surface area, the front pads are just thicker by a few millimeters