Ficm tuners are typically not accounted for in good tuning. I had an idp ficm tuner and idp tuning at one point, and with 19p/30s and a stage 2, it was extremely smokey. Set the ficm tuner to badically stock and it cleaned way up. Basically the ficm tuner changes some ficm parameters, as normal tuning doesn't touch the ficm, then with the regular tuning they add pw and timing on top of what the ficm tuner added.
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WHS ^ The only platform that even allows full control over the PCM and FICM is HPtuners in one whole flash.
Its a excellent platform, but the credits for the PCM/TCM and the FICM cost a ton+ in the fee for the tune writer actual files and its a load of money.
So that's why its IMO rare to see some of the larger tuners on HPtuners for the 6.0 and choose to stick with SCT.
When in the right hands, in combination with a HPtuners based all in one PCM/TCM/FICM file a truck can make a ton more power on the HPtuners platform vs a truck on SCT with ICP fooling and other PCM based ICP "tricks" with the same setup.
The truck runs overall better and its less "quirky" The power band is quite smoother as well.
Majority, of the major tune writers files are built with their "secret" tricks (like ICP fooling ect etc) in mind.
So adding a ficm file with actual pulsewidth table adjustments/combined with the PCM ICP based "fooling" will just make the truck smokey and run hot.
You could possibly ask your tune writer to return ICP values to OEM so the FICM/FICM file can actually do its job.
But they may not change it due to them needing to rebuild the file.