As a service to my taxi guy yesterday. Nowadays Grab/Metered taxi guys can now pick up passengers from airport. They were prohibited from doing so not too long ago (last year i think).
Just drop this fella a whatsapp message if your destination is around Sg Long/BMC/Balakong area as he stays near this area. He charges a standard start rate of RM3 and the rest by normal metered rate. Depending on traffic jam i guess and this green buggy he drives can fit 4 check in sized luggage which will be helpful if you happened to need bigger taxis.
It's nice to know that your taxi is already arranged before you even arrived in airport. I messaged him 1 day before flight time & gave him flight information (he needs this to register with airport counter). Just drop down to Level 1 from arrival hall (Level 3). There are also metered taxis waiting at this area. At least airport transfer is not as expensive as airport limo now.