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Message: [QUOTE="Mdub707, post: 1340897, member: 107"] Found a post on PHP's forum from Jay about the rollbacks that might help shed some light: "Basically from the years 2005 til 2007, Ford issues PCM calibrations that existed in the VXCF*** family. Depending on when that vehicle was flashed, whether or not it was a F450 with 4.88 gears, your standard federal 49 state F250 / F350, California model, cab and chassis, etc... will dictate what the last three alpha numeric characters are. On my personal 6.0L PowerStroke, I purchased it with VXCF9H4 as the original PCM code from Ford. We will use this for our example. This is the newest ford updated calibration available which was designed to fix several issues. Only problem with that is the methodology behind the fix. Chronologically, Ford released the updates VXCF0***, VXCF4***, VXCF5***, VXCF7***, VXCF9*** There was many files in between these years, but for the purpose of this post, these will suffice. Plus they are the most common codes I see so hopefully many of you can relate if you know your strategy. For the purpose of the PCM Rollback, Bill analyzed each of the individual strategies and selected what he believes to be the best suited as a base. The calibration set in which he deemed best for this series is VXCF4***. Here is why: VXCF0*** isnt terribly by and extent however it does possess it's share of issues since it was the first strategy released. Most of these issues were in the form of 'inopportune' shift strategies / attributes that are not able to be modified in the tuning. VXCF4*** and VXCF5*** both function using the EBP sensor to actuate the veins in the turbo. Due to the turbo running off true readings from the engine, it is naturally going to run more efficiently to produce better throttle response, power, and fuel economy VXCF7*** and VXCF9*** both operate off what is called "Inferred EBP". This was the Ford engineer's choice to fix the exhaust back pressure(EBP) sensor from clogging. Basically the concept behind the inferred EBP was to make the engine run without a mandatory reading from the EBP sensor. This function allows the veins in the turbo to regulate the exhaust back pressure based off an estimated EBP MAP rather than how the engine sensor is actually reading. Does the PCM ignoring the EBP sensor fix the issue of the sensor becoming clogged? Yes. Does it cause issues for vehicle performance and fuel economy? Yes. These examples are just the tip of the iceberg in relations to the changes made from one update to another. I believe it serves well enough to explain why we rollback the PCM calibration the way we do. For those that need the cliff notes version, VXCF9H4 rolls back to VXCF4H2. ' VXCF4H2 run gooood ' (Read in your best cave man voice) - Jay" [/QUOTE]