they have one specifically for breathing. you may want to get the one for INFECTION and DETOX too, just to support it.
the snoring could be a respiratory infection which if you do all 3 of those herbal remedies just may nip it in the bud. they are clear, odorless, and tasteless and you can put it right in their water dish and they will not taste it.
older cats tend to snore and get a weak respiratory system too. but there is something still going on and if you haven't dewormed your cat before, would be a good idea to get the parasite one called PARALIXER too. i have a 10 year old that's been on the above mentioned herbal remedies and his loud breathing sound has gotten much better in 2 weeks.