Brakes Pulling to one side after Carbotech pad install
I purchased Carbotech AX6 pads and installed them on the car with new rotors, cleaned slideing brackets and old hardware. The car now pulls to the left. This is the first time I've tried a high performance pad.
I know it seems as if the brake pads would be the issue on your car, as it didn't have this problem before you installed the pads - however - the only difference between the Carbotech brake pads and your stock pads are going to be the friction compound and the thickness (as they're new and not worn). Dimensionally, the pads are the same. I've been around Miata brakes for a while now, as well as Carbotech pads, and can probably tell you that something is up with the caliper on the side it is pulling towards. When you installed the new brake pads, you probably had to retract the caliper pistons back into the caliper to accommodate the new pads. Perhaps something got jammed when doing this causing the caliper to not retract fully when the brakes are released. This would cause the pad to drag on the rotor, therefore making the car pull to one side because of the drag. Also the pad clips can also cause a pad to not move like it should. I'd recommend removing the pad clips and driving the car to see if it still pulls. This will allow the brake pads to move freely within the calipers, and would eliminate any drag associated with the pads. If it still drags, there's a problem with the caliper. Please be advised, removing the clips will cause the pads to bounce around within the calipers and cause clunking noises when going over sharp bumps in the road. We run our Spec Miata racecars without the pad clips to eliminate the chance of a pads dragging. The pads will stay in place without the clips as proven by racing our cars without an issue for 7 years now, they'll only be "floating" inside the caliper bracket rather than held in place by the clips.
Also, one more basic thing to check is for air in the brake system by bleeding the system. Air in the system will definitely cause problems, as the air pocket will cause the fluid to not move through the lines and calipers like it should. I'd recommend bleeding the entire system while you're at it.
For what it's worth, I use the AX6 pads on my 1999 Miata street car and absolutely love them! The don't squeal too often (maybe just a bit during low speed stops, like in traffic), don't produce much dust, and are easily the best stopping pads I've EVER felt on any car! They are drastically different than OEM or OEM replacement brake pads, so if you're used to having OEM type pads, the AX6's are going to feel entirely different and will take some getting used to because the grip level is FAR greater than the OEM pad compound. Please don't blame the brake pads too quickly and try to work through the other components of the system before tossing the pads in favor of the OEM pads again. Like I said before, we know the Miata brake system very well and wouldn't put it past being a flaky brake caliper (we rebuild and modify Miata brake calipers for race use, and I've seen some pretty gnarly ones that barely even worked anymore because they were so nasty). Bleed the system first, and clean the slide pin bolts that attach the caliper to the caliper bracket. Take you some brake cleaner and flush the holes for the slide pin bolts within the caliper brackets of all the gunk and old grease. Clean the holes as best you can with a rag and screwdriver, then use some wheel bearing grease and put about a quarter (25 cents) size dab of grease inside the hole. Also clean and polish the slide pin bolt, and grease it before reinstalling the caliper. With the air bled out, and the slide pin bolts freed up, I bet you everything will be working MUCH better!