Hi,
Not sure if you mean Perlis or Penang
IF Penang, it is one of the best place to ride in Malaysia where you have the popular Penang Hill where you can find challenging single tracks miles after miles! You will have a blast at Penang!
IF you mean in Perlis (the border town of Thailand)
I rode there once, it is usually riding at plantations where it is not too hot, nice flowy trails, they used to have big riding event annually where more than 1000 riders will be participating. Also you can go over the border to Thailand where there are very good trails there.
too bad there is not much mtb forum in malaysia where you can locate riding group, but please go to ask in bike shops am sure they will be able to hook you up.