Even at a low level I got an additional knot with an engineer, and I notice a few MN SS3's really
moving 33-34 knots, so it might be beneficial to level an engy for these.

I'm not a sub player in any respect. However that MN SS4 is really confusing since it
looks like a SS1 and it's harder to hit.

Ok the MN line for subs is a combo of the US and the KM. Their torps have decent power
they're fast and small enough to be SS hunters while retaining enough DP and
resistance to survive BB hunting. It is a multipurpose sub with speed and size as
advantages but nothing particularly special about it. It doesn't have proxi's or really
hard hitting torps like IJN or UK, nor does it have obscene DP and SD like the UK line. I
consider it a smaller faster US sub. Aside from the MN SS3.

ur able to fire 8 freaking toprs out the frunt. while km gets 4 =/ keep the fing deck
gun give me more tubes so im a freaking sub not a cruiser

According to this:

http://opennavyfield.com/forums/index.php?topic=63.0

It has the biggest HE damage. And no, it doesn't have the longest dive time, also
according to that.

the splash is as good or more good than KM one, 6 torpedos, less fails than japs, good
overheat, small size, i just love them, for me the only advantage that have the KM ones
over MN, is the proximity torps, besides that nothing more

I know this is gravedigging, but just for future reference for anyone who looks at this
thread (like i did):

Nobody pointed out the MN has the best dive time? (10 second more then other IJN tiers)

MN its better than UK, more damage per Torp and better movility also the damage area is
superior

So then UK or MN?

MN subs have plenty of tubes on all tiers and their splash radius is really big... the
torp range is very low, but together with the splash damage you only have to learn your
torp range and can fire spreads that the enemy can hardly escape.

About the speed... my MN SS1 was faster than my USN SS1...