That story is like 90 percent myth, I'm sure Chinese engineers knew "proper" TWR of the F-119 engine and even then I doubt they'd actually care too much other than made have a general reference but overall WS-15 is made tailored to PLAAF specs and not trying to one up the F-119. The fact that some people are saying the US "falsified" TWR data on the F-119 is also another myth, F-119 do indeed have a TWR>9 without the square nozzles and I'm pretty sure most serious aviation enthusiast is aware of this fact. I mean unless your one of those fanboys no one actually thought F-119 is going to have a >9 TWR with that giant heavy TVC nozzle lolThat's the story of the WS-15. China believed the crazy T/W ratios the US published for the F119 and moved mountains "matching" it with the WS-15, and then the actual weight got revealed in .