Buying an 05. Questions?

[AKDuramax]

Just about to pick up and 05 3500 srw quad cab long bed, 6 speed, 4x4 with 56k miles on it. I'm gonna do intake, exhaust, and gauges, but was wondering what yall recommend for chips/programmers? I want a soild 500rwhp. trying to determine the best setup. Plan on a clutch, fuel system, injectors and turbo down the line also, just dont know which ones to go with. This is my first common rail cummins.

Thanks!

Kevin