i don't think i said it was physically de-rated...just rated at less than its full potential so there is some power in the bank for performance loss with altitude. for example, if the engine is putting out 200 hp and working at 75% of its possible output to hit the MP redline, there will be a point at which its working at 100% of capacity to deliver that 200 hp at some altitude/temp. you should never actually be putting 265 hp through the drivetrain unless you're exceeding redlines. its the same idea as the c-20 in a jetranger being 420 hp but only delivering 317 (i think) to the tranny. without that power reserve it would be like...well it would be like a jetbox with a c-18 i guess...(thankfully i never had to experience that)