Question about a native

There is a setunitspeed native or something along those lines, if you go
SetUnitSpeed(u,1000) then go
call BJDebugMsg(I2S(GetUnitSpeed(u)))
would it print 1000 or 522?

It should say 522, since in the gameplay constants max movement speed is 522 by default, thus not allowing functions to raise it higher.
It also might return their default, since it might not work if you try to set it higher than max.

You'd really have to just test it.