As for CAT's needing parts to get an uprate, check the Cummins techs and they will tell you the you need to change parts too. If you change parts on a CAT to increase power then you still have your warranty. If the engine in question is an electronic version, there isn't anything that can be done other than what a tech at a dealer can do. It is all in the programing. If it is mechanical then a twist of the 'fuel screw' will do the trick.
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90 W250, 5-speed, isspro gauges, 16 cm2, K&N, Borgeson shaft, JRE 3" exhaust, Banks Intercooler, Lucas injectors