Plenty of time.

When you get off the RJ flight,get the train to the main terminal and there will be an escalator to your left leading to domestic connections channel. That channel is super empty and super fast and you will go thru immigration and security there. Don't go thru arrivals as that will take a lot of time.

Also even if you are booked in Y on KUL-LGK sector,show your RJ J BP to the MH lounge reception and they will let you in.