Calipers have shown signs of scorching, both sides, changed pads a few months ago, never seen this before.

You should be using ceramic composite rotors. Ceramic has become the highly competitive field of aftermarket Brake Pads as well, Lots of people are switching to ceramic pads for performance reasons.
Almost any pad that will outperform the factory original will be hard on rotors. These pads may be noisy and wear quickly as well. They're designed to do only one or two things well — at the expense of all the rest. The OEM components, on the other hand, are required to meet a wide range of requirements before they make their way into production. Deviate from the factory pads and you run the risk of upsetting an unexpectedly delicate balance. Engineering 101 is all about trade-offs. It is possible.

What is the difference between semi-metallic and ceramic brake pads?