I don’t have direction for the tune- exhaust kits are available at all the normal places- summit, jegs, etc. afaik our vendors here don’t offer any.
I will say since you just got it- put a couple thousand miles on before doing anything in power side to make sure you are solid.
600 hp to the ground is gonna shorten life, more than that and you need better pistons or that life becomes a week.
Start out replacing the egr. Probably not done yet and your 75% at done if they left it stock. Start feeding more fuel and it will be a problem quick.
You’re probably gonna have a hard time with tunes because you introduced yourself just like a bot or inspector from the epa. Save the spotted tree whales man.