Its just a mod to to the sub.cfg files changing what speed you get for each throttle setting. A personal preference, at one third ahead for example will give 7 kts in calm waters and so on. Anything faster than that planes seem to spot you more often. They are more dangerous than a destroyer after 1941, and are the sole reason I have never made it into 1942.
I think I modded the deck gun as well to work in slightly rougher seas. In GWX deck gun only works in good conditions, I thought this was a bit unrealistic. After all you still have the problem of hitting the enemy.
Also, you are probably right about Stiebler4C_Addon_for_V16B1 being where it is. I just checked my files for NYGM and that file is optional when you install NYGM.
Kudos to you in any case, I don't know how to make Ahnenerbe WideGui 1920 x 1080 Final work with my NYGM. I'm not that smart so I haven't really tried to get it to work.
Cheers Graeme