I've heard so many things about the ex no.2 badminton player ong beng teong. one of many things i've heard is that he is a great coach and his training is very effective. has anyone else training with him before?? his badminton academy has even got a website: www.probadmintonacademy.com
I did trained with him before when I was 11 or 12 years old. One of the most effective training and you need to have great mental strength as well. Very hard training. I'm not sure how his training now but as for my experience it was the best. You should give it a try.