Does this deck need ramp? Domri Rade in place of Managorger Hydra?
Are there enough blue decks to consider running Gutteral Response?
4xSignal The Clans or Collected Company would smooth out getting the creatures you need; is that important enough?
Isochron Scepter becomes a copy spell on a stick; find some way of getting 2 in to the deck?
Relic of Progenitus or Grafdigger's Cage in SB vs graveyard manipulation decks.
Replace Mutagenic Growth with Predator's Strike?
Trample and Double Strike are integral to this deck; is it worth it to add 2+ Rancor? 2+ Runes of the Deus? Not enough creatures for a Strength in Numbers really.
Dismember, Clan Defiance, and Firespout all were close picks for the SB.
Hull Breach in place of Destructive Revelry in SB?
So tempting to SB 4 Vexing Devils, perhaps in place of Lighting bolts or other board wipe.
Good cheap sideboard cards: Boil for blue decks, Rending Volley/Combust for Splinter Twin, Molten Rain for Tron and multicolor control/midrange, Shatterstorm/Shattering Spree/Vandalblast for Affinity, Dragon's Claw for burn, Pyrite Spellbomb for Kor Firewalker. Scouring Sands vs Thopters. Ratchet Bomb is a nice multi-purpose card as well.