The valve is fully closed so you should be good. maybe under hard acceleration you might get some leakage through. I plan to take mine out eventually however have had no issues otherwise.With the egr being software deleted, is it good enough? On my jeeps the egr valve hangs open a bit, by design, it always allows some egr in. So in the 3.0ps is it a fully closed system? Or should one get the physical block off plates?