So to be brief, this modpack is similar to tekkit, but different, in the sence that there are completely different mods (see list below) Voltz is a more realistic, industrial-oriented pack, even more than tekkit, that has a lot of cool features from fission reactors, radioactivity, Assembly lines, missiles, explosives galore, conveyer belts and much moar!
As i am not very good at explaining things, follow this link to the wiki to learn more!
Heres a LP: http://youtu.be/mHnV05x5FxM
In my opinion, this looks like a very interesting modpack to check out. I mean, the tekkit server was pretty much abandoned, why not give this a shot? Also missiles.
Edit: im not sure but i think its in minecraft 1.4 as well.