Do you have a federal emissions truck? If you do, you might not even get the light. If you do, it is a $50 fix. You can get the kit from kennedydiesel.com Also, I am assuming you are doing the "off-road" system which has the pipe to replace the cat. If you are doing a cat-back, there are no worries.
I've had the MBRP SS 4" exhaust and the Diablosport Predator for 2 weeks now, towing and highway driving, and so far - no problems - just more power (and about the same mileage - a little better when towing). Thanks for all the suggestions when I was making these purchase decisions.
I have thrown the egr code while towing with my edge up in the hot setting, but this only happens when the truck is dumping an extreme amount of fuel out the tail pipe. I have a silver line 4" turbo back no muffler and also an diamond eye true down pipe(what a bear to fit on the truck) Helped with th egt's though.