Edit: 3-27-13
Let me know if I'm missing anything...

General: 1x Kumano, Master Yamabushi

Creature (27)

1x Akroma, Angel of Fury
1x Balefire Dragon
1x Chandra's Spitfire
1x Charmbreaker Devils
1x Dragonmaster Outcast
1x Dwarven Blastminer
1x Fortune Thief
1x Furnace Dragon
1x Galvanoth
1x Goblin Sharpshooter
1x Goblin Welder
1x Gorilla Shaman
1x Greater Gargadon
1x Hamletback Goliath
1x Heartless Hidetsugu
1x Hellkite Tyrant
1x Hoard-Smelter Dragon
1x Homura, Human Ascendant
1x Inferno Titan
1x Kamahl, Pit Fighter
1x Kumano, Master Yamabushi
1x Magmatic Force
1x Magus of the Moon
1x Soulbright Flamekin
1x Taurean Mauler
1x Urabrask the Hidden
1x Viashino Heretic

Land (33)

1x Forgotten Cave
1x Mikokoro, Center of the Sea
27x Mountain
1x Shinka, the Bloodsoaked Keep
1x Shivan Gorge
1x Spinerock Knoll
1x Valakut, the Molten Pinnacle

Planeswalker (1)

1x Koth of the Hammer

Sorcery (13)

1x Banefire
1x Blasphemous Act
1x Chain Reaction
1x Geosurge
1x Granulate
1x Insurrection
1x Mana Geyser
1x Meltdown
1x Pillage
1x Recoup
1x Red Sun's Zenith
1x Shattering Spree
1x Vandalblast

Instant (10)

1x Chaos Warp
1x Comet Storm
1x Into the Core
1x Mogg Salvage
1x Pyroblast
1x Red Elemental Blast
1x Seething Song
1x Shattering Pulse
1x Wild Ricochet
1x Word of Seizing

Artifact (10)

1x Basilisk Collar
1x Caged Sun
1x Gauntlet of Power
1x Goblin Charbelcher
1x Ichor Wellspring
1x Mycosynth Wellspring
1x Quietus Spike
1x Ruby Medallion
1x Spine of Ish Sah
1x Staff of Nin

Enchantment (6)

1x Blood Moon
1x Braid of Fire
1x Gratuitous Violence
1x Mindmoil
1x Stranglehold
1x Vicious Shadows

Kumano is really a great commander imho and Braids of Fire is amazing with him. :)

My first thought was that 34 lands is very low especially with such a bunch of expesinve and/or mana hungry creatures. Imho cut some of the weaker pingers and go up to at least 36 lands and add more mana artifacts.

Second thing to notice would be the lot of blue hate you play, seems like your meta is overwhelmed by blue control decks, countering and stealing your spells?
If that's really the case you should consider, or almost auto include this card from the upcoming Commander decks.


Other card I would add would be:
Sword of Kaldra, it's like Basilisk Collar, a bit expensive, but can also make a big beater out of any creature you have. Also if you add the Sword, Shield of Kaldra and Helm of Kaldra are also worth to consider.
Thornbite Staff would add to the pinging theme, also a lot of your pingers a shamans.
Also Grafted Exoskeleton is just great with Kumano and so many other Pingers.
Sword of Feast and Famine is also great with Kumano on the battlefield and another card to protect him.
Godo, Bandit Warlord is great for tutoring all these equipment, and an incredible beater.

Hoarding Dragon is another great red tutor, and tutors in red a rare thing.

Also add Goblin Matron, Goblin Recruiter, Goblin Welder and Tuktuk Scrapper imho to get easier access to your artifact hate and other goblin cards. Also Lightning Crafter will be happy about this. :)
Kiki-Jiki is another great goblin to add, but this depends on how many enters the battlefield effects you play imho.
Stingscourger is another Goblin to be considered.

Inferno Titan is an on theme beater, that synergizes well with some other cards in your deck.

Think about Tormod's Crypt and Relic of Progenitus to add some graveyard hate to your deck. Also Mimic Vat is a kind of Graveyard hate.

I hope this will be helpful to you. :)

Thanks for the comments.

In some playtesting, the lands have been ok. I haven't been able to play this live very much, which would be the real test.
I have a pretty diverse meta, but there definitely are quite a few control decks floating around. If I get a match without one, I'd probably consider another deck. And (as you could probably tell) there are just tons of artifacts in most decks I see.

I'm trying to avoid mana artifacts and equipment as much as possible so as not to inhibit my artifact hate. The artifacts I have are a bare minimum for that reason.

I'm not sure on the goblin tutors as my goblin count is pretty low.

Stranglehold is ABSOLUTELY going in. It's amazing for this deck, and globally.

hoarding dragon is probable.

goblin welder and inferno titan would both be great, if I can trade for them. I did just get a mox opal and a spellskite at last week's FNM, so I do have some trade ammunition.

Updated.

By my count, you have 10 artifact hate cards in your deck right now. Now, maybe your meta requires that, and the wellsprings help with that, but I think I'd rather have a Mind's Eye or Candles of Leng or something to draw. Then again, if the idea is to not soak up so much mana, then I'm sure there are alternatives. Seer's Sundial, Grafted Skullcap, Urza's Blueprints. Also, as far as the artifact destruction itself goes, maybe replace one with something that can hit something besides artifacts, like Pillage or Aftershock (a personal favorite of mine, especially in mono-red). There are others, like Fissure Vent or Icefall (which could interact well with Kumano, but that depends. Sure, you generally control when creatures die, but do you really want to have repeatable land destruction? Again, it depends on how cutthroat your meta is, but I can imagine this getting very mean very quickly.

Strata Sycthe is great in any mono-colored deck that ever attacks, and is especially nasty with Balefire Dragon.

Um, other than that, looks pretty good.

The artifact hate is definitely a theme overall, which makes running artifact draw engines a little iffy. My meta has certain archetypes that the excessive hate excels against.

I don't want to run LD. In general, I think of that as far more un-fun than artifact or creature hate.

Edit - 3-16-12

I got some nice legends over the last few months to add to this. Goblin Sharpshooter is amazing, and I can't wait to see if Goblin Welder is as good as I think it is.

3-27-13: Edited to latest build