The terms are pretty good for Malaysian cost of living. Base or Hubs as they call it is subject to manpower requirement. KLIA being the major hub that requires most manpower but other hubs such as Penang, Kinabalu and Kuching may also be available when situation requires it. KL is the most hectic of them all, the smaller hubs seems to suit calm, easy, resort lifestyle.
Taxation applies to basic salary only and all allowances are currently not taxable thus making the money in the bank pretty good. On top of that the Providemt fund (EPF) contribution of 12 % additionally by the company every month on total package is savings that you don't take notice of.
The cost of living index for Malaysia is something that most people don't take into consideration. Malaysia is still considered cheap in most cases.