Is the check engine light on?
Judging by your post it doesnt seem you failed because a MIL was present, but because the catalyst and evap MONITORS were not ready..
If the light is on..how long has it been? The evap system could be not ready because your gas cap wasnt screwed on right one time when you got gas.
Catalyst may not be ready because of the mods and it has a code or because it cant/hasnt gone through a full drive cycle..
Your best course of action is
Is check engine light on?
What codes are present...
Then you can see whats next..