Mana sinks like the abovementioned Figure of Destiny, and Ashling the Pilgrim, are some of the ways to make use of all that excess mana. Firebreathing effects can be the theme of the deck, with Lightning Berseker as an example. These will be able to stand on their own without Braid, and just become stronger with, which is pretty important if you don't want to fall flat without braid.
If you're playing Managorger without Mutagenic Growth to back it up against the ubiquitous lightning bolt, you're doing it wrong. That being said, a painful version of miraclegro is possible with gorger, only more painful in modern (kinda like delver).
Any particular reason to use that terrible card (really? giving your opponent 5 life while playing burn?) over Anger of the Gods or Pyroclasm?
Apart from hardened scales to up the ante, Managorger can team up with friends like Kiln Fiend and Nivmagus Elemental, or even Chasm Skulker if you're going with cantrips like Gitaxian Probe.
I would play plenty of the phyrexian mana spells - Gutshot, Noxious Revival.