Like The name says the bc api do not allow Custom pipes that transport BC energy without powerloss.
I am working on my Custom pipes (they are not as good as bc pipes but they have special uses that make a lot things easier) and i have to fight myself with the powerloss. But the new BC power says there is no powerloss in transportation. Yeah and there is the trouble. You have 2 ways, make a bc addon and make pipes like bc and have no powerloss or make your own pipes and have powerloss.

Thats why i request a api extendsion for custom energy pipes.

Hi @Speiger - do you mind posting and discussing on http://mod-buildcraft.com/forums/index.php?board=4.0? I'm trying to keep github issue to things that are scheduled (see https://github.com/BuildCraft/BuildCraft/blob/BuildCraft-5.0.x/README.md). I'm closing this for now, but it's always easy to re-open a gitub issue.

Thanks for your help,

ST