SLA's for different environments

Is there a way to change SLA assertions based on what environment we are running against?  For example, we have Environment variables set up for Dev/QA/Prod.  We know that Dev will be slower and we don't want to fail a test based on the SLA, so we would like to be more forgiving there.  If we are running against Prod, we would like the assertions to be much more realistic.

Is there a built-in way to do this that we're missing?  If not, can it be done with a script assertion?

Thanks