pounds weight/heaviness - not thrust of engine:
Perhaps not the exact same situation but analogous perhaps anyway:
[March 2014]
"...
The company had already begun a redesign for the IBR as part of a movement to reduce overall engine costs, according to both Bogdan and Pratt spokesman Matthew Bates. The new design replaces the current hollow blade design with solid blades, which allow the company to use simpler, and hence cheaper, manufacturing techniques.
That redesign will add roughly six pounds to the engine; although the engine in question was a STOVL F-35B model, the IBR redesign will impact the engines for all three JSF variants. While weight is closely monitored on the F-35, Bogdan did not seem concerned about the extra weight....
F-35 Engine Part to be Redesigned | Defense News | defensenews.com