I need to find out what mission tree leads to the ability to manufacture Improved High Drain Power Cells. Anybody know what tree leads to this?

did you do the high drain tree first, i suspect it's part of it but it's hard to tell because the improved drain entry was written by an enigmatic jerk who just said you need relevant manufacturing experience.

But i suspect it's in the same ball park as the high drain

http://vo-wiki.com/wiki/Manufacturing#High_Drain_Power_Cell

the path to your hearts desire is illuminated in this thread and links therein...

https://www.vendetta-online.com/x/msgboard/1/30886

woohoo i unlocked SL and IHDPC within the same week

Lee I have maybe told you this 27 times! Man you don't listen lol

Thats lee for you, idiot as always.