How will a gas engine react to an egr delete?

I'm not deleting my egr, I'm wondering what it would do. This is a normal road car I have well use it for example a 99 Honda accord, lightly modified, 35mpg, little more power over stock. I know having a working egr will lower cylinder temperature, decrease nox, and make it burn slower. If it is taken off and the cylinders are hotter what does that do for gas mileage? I assume the effects will be similar to slight timing advance, correct? It will also lower intake temperature too? Do race cars have egr?

I'm pretty sure the egr system is used to heat the intake and allow the car to run leaner using less fuel. Without retuning your fuel delivery it may actually lose throttle response if you alter it. You'll almost always lose mileage tuning for power, race cars don't care about getting good gas mileage.

Ok, so let's clear some things up…

First, no, EGR does NOT entirely "reduce cylinder temperature"… It increases the average temperature, but reduces the PEAK cylinder temp. The peak temperature is what creates excessive NX emissions. It also reduces power. Think about it… An engine that is ingesting even 95 degree air in mid summer, is not going to have a lower intake charge by injecting exhaust gas that's at 700 degrees.

A properly tuned car will run better and emit less without EGR than with it. I capped the EGR pump on my mustang and it passes emissions every year, as well as has more power and gets better gas mileage because you can advance the timing MORE on a clean intake charge than on one that's been heated superficially by exhaust gas.