MALAYSIA CUSTOMS REQUIREMENTS
i. Gold Coins DO NOT attract any type of customs duties.
ii. Silver Coins however, DO
MALAYSIA CURRENCY CONTROL REQUIREMENTS
i. Non-residents & residents travellers are allowed to bring in ANY AMOUNT of foreign currency notes, including travellers cheques, upon their arrival in Malaysia.
If it exceeds USD 10,000, all you need to do is DECLARE it and you're free to go, so remember to do it.
For more information, please click the official link to the government website.