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The EGR(exhaust gas recirculation) system allows for more aggressive spark timing, so certainly doesn't hurt performance, quite the opposite.
NOx is a toxic emission that spikes to very high levels when cylinders heat up too much.
Cylinders heat up when you accelerate or otherwise load up the engine.
Heating up the cylinders also causes pre-ignition(pinging/knocking) with 87-89 octane gasoline.
If you add a bit of exhaust gas to the intake as engine is loaded up it will slow the burn in the cylinders which keeps the heat levels down, so less NOx and no Pinging with regular gas.
Less NOx was the big concern, no pinging was a by product but.......a bonus since the only other way to prevent pinging is to run more expensive higher octane gas or to change the spark timing to ignite the gas before it can pre-ignite, which lowers power and so MPG as well.
Yes, you can program EEC-V computer to ignore EGR system, but you will also have to change spark curve to prevent pinging on Regular gas.
It is easier to add a bung on a header pipe and restore the EGR system if you still have the parts.
Any exhaust shop can add the bung with correct placement and size to match existing EGR tube.
Your lungs will thank you along with any kids or grand kids you may have now or in the future.
Last edited by RonD; 10-09-2016 at 12:04 PM.