I have an 05 5.9L 2500 with stage 2 cold air intake,4inch straight pipe to a 5 inch magnaflow straight through muffler. Also lots of upgrades to the tranny, should I go straight to a programmer or chip or is there some other stuff I need? And what programmer or chip should I get I'm wanting 500 hp

 

gauges and fuel system upgrade...

get yourself the following gauges:

rail pressure
trans temp
pyrometer
boost pressure

and for a fuel system, the airdog150 or fass150 fuel systems are decent choices for a 500hp truck.

you want to make sure you don't run out of fuel supply to your cp3 pump or you could burn up the cp3 pump or even worse: have rail pressure jump around too much leading to a cracked injector.

after you get your gauges and your fuel system, and you are sure your trans is built strong enough... (as in billet shafts, good valve body, and heavy duty torque converter) then you can go for a smarty programmer, or go with the custom EFILive tuning.

you may want to think about a turbo upgrade in the near future as well...stock turbo is not going to cool down 500hp worth of fuel. you can always do head studs and get a budget twin kit and throw a S475 under your stock turbo...that will for sure cool it off, but your cool air intake will be garbage after a twin kit..

you might also want to get either an aftermarket intake horn, or go to a junkyard and see if you can find a 2nd gen 24v cummins (like mine...98.5-02 year series) and get the intake horn from it...the 3rd gen intake horns are a big choke point in the intake and should be replaced for twin application or higher than stock boost applications.