Vac on the exhaust? You could put a magnehelic gauge on it and see if it's going above atomphere, if so it's not keeping up. Anything below atmosphere and I figure it's helping the engine, but you'd need to do this on a straight piece of "duct" with non turbulent airflow
You should stop testing with vacuum pump, most do not run and gives a real different power output.
Vac on the exhaust? You could put a magnehelic gauge on it and see if it's going above atomphere, if so it's not keeping up. Anything below atmosphere and I figure it's helping the engine, but you'd need to do this on a straight piece of "duct" with non turbulent airflow