I did many similar changes as suggested in this post in my custom
DA codex, you can download it here:
http://www.fancodices.com/
For the nephelim jet fighter, I did change the missiles so
STR 8 and decreased its cost.
For terminators, I changed to so they come at 35 points each with lightning claws (since it is their worst gear).
Then they can upgrade powerfist and storm bolter (stormbolters are salvo 2/4).
They can also upgrade to thunderhammer and storm shield ending up at their original cost.
I also considering making terminators and ravenwing troop choices and get rid of the dependency on named characters (which are not always allowed in tournaments) to build a good terminator/bike list.