Ma Yuen / Go-Go

Some new (to me) pills have been floating around Singapore/JB recently, and I'd like some help to identify. I've got a language problem which stops me getting details from the supplier.
"Ma Yuen" (horse pill in Cantonese) is most probably ketamine. It's a dizzy and slightly hallucinatory feeling. Confirmed?
The other is sometimes called "go go". Small pill, with sweet, chocolatey taste. Good feeling, but you don't sleep for at LEAST 24 hrs. after dropping this stuff. Any identification?

well "go" or "goey" is a popular australian slang term for amphetamines so the second pill is probably what we'd call a speed pill.
the first one does sound like a ketamine based pill but cant really know for sure...

The horse pill you mentioned could refer to the ferrari logo pills that were around a while ago. I think they were weak MDMA.
Um "sweet, chocolaty" taste?
I don't think that sounds like a chemical!