It's interesting how RRs have gone to sameness/interchangeability over pure performance. CSX has some heavy AC4400CWs/SD70ACes for pulling but those may not be increasing in number--lol.
Today's railroads are increasingly about standardization which helps in developing algorithems. 6000 HP killed the EMD units tooj(along with questionable traction motors). The BigBoy had similar power and so the DD40AX. There seems to be a cycle of these high horsepower units.
Of course EPA and train length restrictions don't help to create a world where 6000HP multiple units are practical
I'm pretty sure China is all over the 6000 HP club.
Richard
IIRC, they were built with a 6000 hp V16 FDH powerplant installed. At some point they got repowered with a V16 Gevo powerplant - Same 6000 hp rating. In the past year, CSX has down-rated them to 4600 hp, and had GE adjust the traction control software so that they were more compatible with 4400 hp ES44AC fleet.
I an not sure about 'storage' - I think there may have been lines of them waiting for the Gevo transplant at one time.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
I'm pretty sure CSX 601, spirit of waycross entered in mid 90s at 6000HP. Trains magazine did a special on these units in their locomotive book. They've been featured in the magazine as well. You may have better luck getting more info on their blog.