That's very promising. For the record, the Japanese problem with being effective early on was not their sonar systems. Even early war systems had a detection range of about 2500 yards. Their passive was very good. One of the biggest issues I've seen with stock sonar in SH is that the ranges are so short (1200 yards). If you go deep, you get beneath their detection cone and they only have approximately 300 yard "sweet spot" where they can detect you on active. They rarely succeed to acquire you in that "gap".
Changing the sonar files is really tricky to get it right--especially since everyone has an expectation/personal definition of what is "right". I will say that the most important tweaks are range (obviously) and sensitivity. A typical sensitivity rating is 0.05. Changing that value to 0.06 makes a Big difference in their chance of detection. Another big aspect is "Surface Factor" which is determined by aspect angle of your boat. Keeping the enemy in your baffles or bow on gives you a huge edge to remain undetected--just like when doing surface attacks.
I'm currently playing SH3 but am considering sparking up SH4 again. It's been a long time since I played either one... I modded the early/mid war sonars in SH3 by extending their range to 2500 and it adds some challenge. I think doing the same in SH4 would be far too aggressive since US boats don't go as deep.
Good Luck with your mod. I'm a big fan of the kind of work you're doing!
