You yourself said in a previous post that dropping down to 18 lbs boost vs 25 lbs should've cost up to 500 bhp (I'm willing to account that it's a typo). On various sources, from Wikipedia to info in the two Hornet books I've referenced don't note that much of a discrepancy. They also don't note when or why the changes happened. You have to remember that the Hornet/Sea Hornet were the only aircraft to use the 130 series engines.
The 2070 hp for the 130/131 and 2030 for the 134/135 have been quoted forever in most sources I've read, be it internet or print. But then again, those sources also quoted incorrect overall lengths for the Hornet (37" 9" tail up for F1, 38" 3" for subsequent versions is the accurate figure) until the book Hornet & Sea Hornet: de Havilland's Ultimate Piston Engine Fighter came out about a decade ago (plans were found during he book's writing that were actual DH plans for the Hornet that had the correct info), and that the Sea Hornet NF21 had a top speed of 430 mph, instead of the correct 461 mph. I think that it's safe to assume that the newer info based on what are supposed to be more accurate sources should be correct or at least more accurate.
But even the newer sources quote the differing supercharger boost and power differences between the engines.
Yes, 2090-1670=420hp, I should have been more accurate in that difference between T/O 18lb and low alt Combat 25lb.
Looking at the different tables in the sources, there are differences. This will be due to many reasons, even the Rolls-Royce data changes around. I can see that the RRHT data
differs considerably in the Merlin 100 book in the "Leading Particulars" tables, which look to possibly be from an RAF A.P. on p.194, 195 and 196, where there are International ratings and Combat ratings, only some of which match the Engines of the World table.
It would also seem that there were some censored details at the end of WW2, certainly in the free press.
The Rolls-Royce data presented in graphical form is possibly more useful. Careful reading of the RM14SM Rating graph on p.141 possibly shows the small differences that are sometimes quoted at T/O and low altitude. The T/O 3000, +18lb shows 1650hp rising to about 1670hp @ 1000'. The low gear Combat 3000, +25lb shows 2050hp rising to 2090hp at about 2000',
so there are those differences.
Another detail is that the high boost fuels were changing, the RRHT book often refers to 100/130 fuel and 100/150. There is also mention of 115/150. There are others.