I would actually strongly advise against running
Sorcerer's Wand, even in Sideboard. Any mono-red deck should be as fast as possible, and a three mana equip cost doesn't cut it. Tapping your wizards is also not what you want to do unless you're attacking with them.
Ghitu Lavarunner,
Soul-Scar Mage, and
Burning-Fist Minotaur are best when they are swinging in instead of pinging, especially since they can only ping creatures or planeswalkers.
And while
Magma Spray is definitely a good sideboard option, I wouldn't say it's better than
Shock in the Mainboard. Again, this deck should be aggressive and spell-slinging. With
Magma Spray, you may or may not have a good target for it.
Shock, however, always has a target: your opponent. If you want a prowess trigger off of
Soul-Scar Mage or to give
Ghitu Lavarunner its boost, you don't want to wait for a creature; you want to deal two damage and swing in for some more.