I started with super chips, then to ez, then comp, after that marco's madd cathcher ecm, and now the madd smarty. I could have saved A fortune if Marco would have had the smarty when I first started bombing. The smarty is the best single mod I have ever made. Even if You are wanting to do serious racing it should be first after gauges. After that You will need to work on the trany if You have auto, clutch if You have stick. Then You will be wanting even more and be ready for injectors, don't try to start out small and cheap (You get what you pay for), don't try to go too big either. With stock turbo You wouldn't want to go over 100-125 hp either, spend the money for A quality set in this range(it will save You in the long run). This is the point where I am now and there is not much in this area that can run away from Me. The truck right now is very fun to drive and gets great mileage. Anything more and You start running into much more money and more than one thing done at A time to be fully effective. I am beginning to pick up the parts A piece at A time until I can tear it down and o-ring head, install helix cam, larger more durable turbo rated for the 500-600 hp range and HRVP-44. I've tried all the combinations and spent enough to do this all by now and I hope somebody can learn by My mistakes and save themselves A lot of work and money so they can enjoy the mighty Cummins at it's best.