If you are using a downloader/programmer or if you are just running modified injectors on your 03-07 5.9L Dodge Cummins, then the BD Boost Fooler is a MUST HAVE PRODUCT! While programmers can definitely improve performance, there are still things that they cannot do to allow you to gain optimal power and efficiency out of your engine. The Boost Fooler will allow you to increase turbo boost to compensate for the added fueling modifications you have made. Enabling your turbo to produce more boost will increase overall horsepower and torque and you will lower your exhaust temperatures. The Boost Fooler is even a great enhancement for a stock truck that hauls heavy loads and needs exhaust temperature reduction. Even on a stock truck you can easily gain 5-8psi of boost pressure to help cool your EGTs. You will also see a slight improvement in peak horsepower. The BD Boost Fooler uses a specialized high impedance circuit to allow you to make more turbo boost without setting any ECU error codes. The Boost Fooler is 100% weatherproof and designed for simple under the hood installation. So what can you expect? On any year model Dodge, you will be able to make as much turbo boost as possible with your fueling modifications. It is important to notice that the stock turbos do have some limitations. If you desire extreme levels of turbo boost then you may need a larger, aftermarket turbocharger. Horsepower gains will vary from 10hp on a stock truck up to 50hp on heavily modified trucks. EGT reductions will vary from 75degrees on a stock truck up to 300 degrees on heavily modified trucks. On 2003-2004 5.9L Cummins you will need to physically modify your wastegate to gain more turbo boost. Doing this without the Boost Fooler will result in check engine lights and codes set into the computer. Stock 03-04 trucks should generate 23-24psi of boost pressure stock. With the Boost Fooler you will be able to run 35+ psi of boost dependant on your fueling enhancements. The 2004.5-2007 5.9L Cummins uses an electronic wastegate which is operated off of the MAP sensor. In this instance no modifications to your turbo will be necessary. Stock 04.5-07 trucks typically spike up to 32psi of boost pressure. With the Boost Fooler you will see up to 40psi of boost on a stock truck and up to 48psi of boost on heavily fueled trucks.