Thanks guys, I guess I'll stick with it and see how it goes. Any suggested hunting grounds?
On my third patrol I came across a destroyer task force. I killed their Kuma flagship before getting pounced on by all the others; very nasty chaps indeed, especially considering I was in only 180ft of water! Is it just me or has this mod made the enemy tougher? It took a long, torturous time to sneak away from alive from that one.