HiCustomerand welcome to JA
I see this talked about quite a bit online but what most people fail to mention is that it is not just a simple procedure to flash an engine to a higher horsepower. The first thing that has to be done is you have to look at each engines build up and determine if it has the correct pistons, injectors, camshaft, valves and turbo to make the increased horsepower. For each engine we have done at our shop I spend about 2 hours going over the components of the engine from when it was built and comparing that to what is needed for the higher horsepower and 95% of the time I have to tell the customer that something has to be changed before the higher horsepower flash file can be put in. When the proper hardware is in place then there are no problems with increasing horsepower. It is when someone tries to do it on the cheap by not changing out hardware that they run into a lot of problems down the road. By this I mean that if the hardware is not changed and the higher horsepower file is flashed in it is no longer a matter of the engine might have a major failure it is a matter of when is it going to fail. That is why it is not usually cost effective to the extra horsepower because by the time you buy the parts needed to make the change and pay someone to put them in it becomes a costly endeavor for small increases in horsepower.