Tuning cost typically vary by the three major components:
-research and testing invested in the files
-tools and equipment used to flash modules (including license and subscription costs)
-support for the end user
Often cheaper calibrations are offered by someone who has copied another's work or just made simple edits for added fuel but not the appropriate changes to injection pressure, timing, and smoke limiters to optimize the tune. The best way to choose your tuner is to look at their experience in tuning common rail diesel engines and how well they are able to answer your technical questions. Because most customers are after basic performance calibrations, there is not a lot of customization required per vehicle unless significant upgrades have been made to the turbo, or fuel system.
Our experience comes from tuning high performance light duty trucks and race engines for Duramax, Cummins and Powerstroke engines. We are thankful that Mahindra chose Bosch components for their fuel system as we have worked with quality companies like Exergy perf. for many years on high performance Bosch fuel system components, so it gives us a leg up on the physics and principles of the Bosch components and control modules.
Happy Off-Roading!