not really tho... my fren say if when u rev ur engine.. the muffler didnt make much noice means its ok de.. and also the tip must be smaller then a cocacola tin,..with silence or without silencer, the cops will still saman you for having a big tip. i asked them before.
as for installing a silencer, also depends on which type of muffler. im using RSR magic with 3" tip and RSR silencer. When in idling mode, the bassy sound still can be heard, just that its not too loud.