What would you gain if you added the AFE cold air intake to your 5.9 diesel? Without any other mods what would you notice? if any? Would your EGTS go up? Would the intake work better in conjuction with a chip or WORKHORSE module? Would you need to add bigger exhaust? what is standard size exhaust on the cummins now and if you went bigger how do you do it? Do you add the new pipe right from the turbo and back or after the CAT?

 

With any aftermarket air system you should see your EGTs go down because you're introducing more air to the engine. You should also notice boost spooling up faster and a little more throttle response. When adding chips or modules you almost have to go with a non stock air intake set up to help the engine breathe and keep your EGTs in safe ranges. You also wouldn't necessarily need to go with a bigger exhaust, but 4 1/2" would be as far as I would go unless you're going to be pushing over 600hp. As for adding the pipe you can add it turbo back, or keep the cat in place and go around it. The choice is really yours.