A card you could consider adding to your sideboard is Purphoros, God of the Forge, he's extremely great with the massive token generation this deck has. Goblin Assault is a good token generator but kind of forces you to attack as much as possible. Although, most goblin decks don't mind that. Goblin Wardriver can basically just make your horde that much stronger.

Oh, and Chancellor of the Forge

Thanks for the comments! Purphoros is the next card I plan on adding to the deck, along with Lightning Greaves. I used to have Chancellor of the Forge in there but I found he's generally too costly for the speed of this deck.

Yeah, I figured as much on Chancellor, but it's MAYBE an extra goblin on turn one which couldn't be too bad.

You might appreciate Phyrexian Altar, Carnage Altar, Coat of Arms, and Chaos Warp. Also, Magewright's Stone is an oft-forgotten card to play with Krenko :)

I like the deck a lot! I've never been a fan of Dormant Volcano, though.

(Oh, whoops, Coat of Arms is already here. Maybe Lightning Greaves?)

Really fantastic R/Goblin EDH deck!

Seems really neat, I love the creative combo for infinite redshirts...er..goblins..

Well brewed :3

You need Urza's Saga to tutor out Sol Ring