If you didn't know about AssetsFix.dta, then you most likely won't ever need it.

All price history for testing the Z systems is included in Zorro and in the archives on the Download page. You do not need to simulate your account or use the Download.c script. That is only for developing own strategies with exotic assets, or for testing very special accounts.

When you don't simulate a different account, then you can't get a different result, except of course when you set FXOnly for excluding assets. Z3 is a metal trading system - it works for FX also, but then with much lower performance.