Get an SCT with custom tunes and you'll have more power and lower EGT's. Those generic boxes just have ridiculous timing. What's worse is their transmission tuning, or LACK there of it.

Stock airbox is the best, WITH the stock filter. It will support up and over 500 rwhp. K&N is complete crap in my opinion, had terrible issues with them on all of my offroad equipment, I'd never run one on a forced induction engine... I personally run a pro-guard 7 dry filter, AFE makes a great product.

ebay Item number: 370431395872 , is this any good?

i personally like the sct but decided to run a dp tuner chip instead

Airaid or AFE filter and if you ditch that cat your egts will drop. tubro back exhaust gets those hot gases out faster than a catback. another thing you can try is this. on your edge go to the menu > juice configuration > low end responsivness > select each level one by one and change it to low if it's on highest. With my edge i'm usually between 600-900* driving at 70MPH on the interstate.

This is the 6.0 section. DP is an awesome setup on a 7.3, but on a 6.0, SCT is hands down the best, proven. Everything is electronically controlled on these, and the biggest difference between your 7.3 and our 6.0's is the transmissions. The 5R110 is all electronic, so tuning is how to beef them up for power. They will safely hold 500hp all day long as long, no 4R100 is doing that stock....