Let's just focus on the mainboard first.Cut:
2x Burning-Tree Emissary
4x Experiment One
4x Ethereal Armor
4x Rancor

Add More:
1x Boros Charm
1x Ghor-Clan Rampager
2x Path to Exile

Add:
4x Voice of Resurgence
2x Knight of the Reliquary or Woolly Thoctar (other choices for the slot are Brimaz, King of Oreskos and Tarmogoyf, but I believe the first two are much more suited for the deck)

As is there are 4 extra slots after these changes, I KNOW there is something that goes in that place, but its 5am and I can't remember right now.
If you want explanations for these changes, just ask, but Voice of Resurgence is one of, if not the best card in the deck, simply because it forces your opponent's to cast more things at sorcery speed, and then you can get bigger creatures off of it afterward.

Hi Dorotheus, Thanks for the thoughts. I probably should have explained that this is a fast Zoo and on a budget (budget being not a lot of money and using cards I have). That said I can see why you have suggested what you have, but some are way too slow for what I am trying to do. I am planning on winning this by T4/5. playing three drops that don't add to the damage the turn they come down doesn't help me do this. I will consider the cards, so thank you

Howdy- I run a similar gruul zoo list. If you're going the gruul angle BTE is its strength. I'd drop Ethereal Armor for 2 Burning-Tree Emissary to have the full 4 and add 2 Scavenging Ooze - The ooze helps with the life loss from fetches and also nerfs opposing tarmogoyfs

Afterthought: If you go with 4 bte you'll find that loam lion is a little cumbersome since it cant be slung off BTE. What most people do is run 4 Flinthoof Boar instead. It raises your curve slightly past traditional 1-drop, but the tempo you gain from BTE offsets it. Its an insanely aggro build.

There's my list if you like the idea

Hi Portfolio, thanks for the input. I like Flinthoof Boar and I do like the idea of slimming down the white. I will have a test with it. thanks

Np man- its my favorite deck to take to modern night at my LGS. If you have any questions let me know i'd be glad to help

Actually winning on turn 4 is a pipedream, the capability to win on turn 4 is already what most zoo decks do.

My LCS, is highly competitive as it's an SCG location. I see zoo lists all the time. I also see some of them fail, when they stray away from the idea of more dudes. The decks have two win conditions, get dudes and swing, or burn. Usually the burn is an endgame.
Enchantments do not work in a zoo deck, as they give your opponent more chances to two-for-one you.
I totally understand building on a budget, Voice of Resurgence can be considered pretty expensive for many people. However, everything else I ACTUALLY suggested, you either seem to already have or is under $5. Keeping in mind Woolly Thoctar is actually played in Legacy Zoo, when it exists, and it's under a dollar.

Wow very condescending! Thanks. Enjoy your SCG location and thanks again for the advise.

It had it's first serious outing at GP Liverpool and managed turn 4 wins fairly consistently with two top 4 finishes in side events :)

I wouldnt run brimaz. Maybe cut 3 brimaz and 1 ghor caln rampager for 4 Kird Ape.Because the rampagers are mostly for the synergy with boros charm.

I was running Kird Ape, but I didn't like having that many 1 drops. Brimaz teirs out of bolt range which I have found to be really helpful. I also think Ghor-Clan Rampager is fine without the double strike from the charm. Sure together they are awesome, but 2 mana for 4 extra damage from a spell that cant be countered is still very strong. Thanks for the suggestions mate.

I just took the ethereal armour out. It's been out of the deck for ages and only just realised that it was still listed :) My first draft was somewhat different.

Experiment One was also in for a while and I like how it survived once it had counters and got bigger, but I found that I didn't want to be playing creatures before combat and leaving myself without options during combat so they were removed. I do love them though. Thanks

Elspeth, Knight-Errant is good for zoo, hilarious to give a creature +3/+3 and flying, use boros charm to give it double strike swing for alot of damage

That's not a bad shout. Could be a good sideboard card for when my speed isn't enough. Thanks

no problem bud