I'm in KL as well and also looking for boxer breeder as well. I prefer to get the puppy from breeder rather from a pet shop. I'll let you know if I found any in KL.
I'm looking for boxer breeder as well and I saw your posting that you know one in Penang. I would be glad if you can provide me the information. Currently, I don't have any dogs because I'm sharing a place with someone but I'm moving soon to my own place and finally I can have a dog.