It's standard procedure here to update the software in the engine ECM, DEF/SCR ECM and dash cluster when engine and emissions fault codes are logged. Lots of times the new software solves existing issues and can prevent future issues. I have never see theses updates cause low power complaints. However there is two possible ways things can go wrong with software downloads and I have done them both. First. Make sure TechTool is restarted for truck it's plugged up to. A couple of times I didn't close out the job card I was on and went and plugged it into a different truck. TechTool thought i was still plugged into first truck and if I were to do any programming ,the data from the first truck could have been put into the second truck. The other way ( and this happen the other day), all the ECM's in the truck are programmed with the VIN of the truck they originally came from. If the dash cluster , Vecu , engine ecm or DEF/SCR ecm were swapped from another truck, the VIN's won't match. This shows up when you first plug up to TechTool as Mis-matched hardware. You then have to choose which VIN you want to choose, of course you pick the one on the door. If you choose the other VIN , your truck now get programmed as that truck. In these cases your 505 truck could be programmed to 415 . Dealer should be able to go to "product information " in TechTool and confirm HP and that all Vins in ECM's match what's on the door. That said , we sold a 505 hp CHU to a customer and he used it for a week and loved it. Next week he comes in and says it has no power. We test drive and confirm it. Long story short , we install new turbo and injectors and EGR valve. Still no better. Come to find out , owner changes tires and wheels to full size 24.5" and didn't tell us. It threw the computer off so bad it killed the power. Changed the revs per mile in ecm and all good .