Custom Tunes & EPB Sensor Strategy...???

[SICKS-O]

you may or may not have an inferred ep calibration the only way to know for sure is if you have access to a device that will read the ecms current calibration code.

out of curiousity is your 2004 truck an early or late 04 model? sounds like you are on the right path with your modifications, the powermax turbo and 155s will work well together. have you looked into an egr cooler delete or block off kit? it would be a good idea, esp with the modifications you are planning.