I have an 04 6.0 f350 dually. It's my dd and have made some changes since I bought it. The truck came studded and egr deleted with a 5 inch exhaust system from the down pipe back into two 10 inch stacks. I have add a bank intake elbow, banks ram air, banks iq 2.0 tuner with the six gun and banks intercooler piping. At the moment I'm having a miss on #6 injector and was looking to up the injector size. I would like to put 550 to 600 at rwhp. What would be the best option to get myself there.

 

Here would be my advice if it was me. If your looking for 600 hp. Your not afraid to spend money so here is what I would do in your shoes.
Sell your 6.0L first off they simply can't stand up to big power . Start with with a better platform a 7.3 or a 5.9. You won't be disappointed if you start with something more reliable. This is coming from a guy that has melted a 6.0 right down.