New guy, First truck. Need some engine advice! 3406E power.

What's your boost?

 

There should be some info on this coming from the tech savvy guys, but if I am correct, it's because you're not getting enough air for the fuel that's being fed, that your egts are higher than they should be. I can get over 900 pulling a grade with my C15 quite easy (ambient air temp has a huge bearing on this too) but I am pulling 140,000 lbs with it. Running a 5 axle on flat highways, I personally don't think you should be over 700-750. Air filters good? Next thing to check, no air leaks from turbo, through air to air to engine? Looks like you'll be hauling grain?

 

Check your rack about the jake brake. I had an exhaust valve adjusting nut come off, we ran the rack and after fixing that the jake held a bit better and sounded much smother. I think there was some damage done to the rocker or valve steam, not sure how long the truck ran like that I just noticed it after I put straight pipes on it, but there's a sister truck to mine with the same motor and exhaust and it does sound smother still. Both going up and jake braking down.

 

I feel like your egt's are a bit on the high side as well, I think your lackin quite a bit of air someplace. First thing, inspect air to air system for any leaks. Check turbo fins for any damage and shaft play. Also check the wastegate, make sure its not stuck open a bit or opening too early. Sounds like a jake tuneup kit and redo the overhead is in order. Make sure fuel psi is on the high end of the spec for that model. Make sure fuel filters are good and not pulling restriction. After everything checks out you can most likely get it uprated to a 550, or if you want probly even a 600 file, don't expect the turbo to last though. If the turbo is toast, no better time to upgrade. The 10spd is ok for you now, I'm not a big fan personally. Run it till its junk, then either a 13 or 18 will help keep the engine in its sweet spot.
What rear gear are you running btw?