Well I dont think Sinhals classes is good for HSC XIIth, as their notes are not 100% correct and not according to the board pattern. Many important articles are missing while several out of portion topics are included. Very few of professors are actually good, but the rest are useless.
I suggest Kalrashukla Classes Private, which is way better than the General KS Classes, and has the best professors, including Prof. Kalra and Prof. Shukla himself, covering most of the chapters in Maths and Physics respectively.
I was doing both Sinhals and KS Privates for XIIth, but then had to leave Sinhals, as it became too difficult to manage both. KS Privates is much better than Sinhals.
KS Privates notes are also excellent, each batch has just 14 students, and regular tests on Sundays, as well as daily tests of 10 marks (30 mins) to keep the Students in touch with the current chapters being taught.
Professors like Prof. Vineet, Prof. Mukesh, Prof. Kalra, Prof. Shukla, Prof. Rate, Prof. Dixit, Prof. Somaiya, and some other, will make sure you are studying properly and will make solving papers easier for you.
I have secured 94% in my HSC exams in PCM, and 87% overall, and I think KS privates helped me a lot.