monty

That would require either adding a bunch of red to the mana base, or relying on drawing a Manaweft and not letting it get removed (and having played a sliver deck, I can tell you that they get removed a LOT). Not a good option unless you're already running other red cards.

I assumed the "quad" was from the double strike damage being doubled again after you loop it through lifelink and Sanguine Bond.

Any feedback is welcome, please keep suggestions post-RtR.

First of all, take out Door of Destinies, it's not spectacular even with a heavier creature count than yours and you have a lot of other expensive spells competing with it that more directly contribute to the core strategy. Also, IMO any Standard sliver deck should run green, and this deck can particularly use it - you have no one-drops and only four two-drops, no mana acceleration, and no control elements, so any half-decent deck will have already won by the time you can get rolling. Bringing in green would give you more mana and 8 more cheap slivers.

If it's not a problem of affording them and you're just refusing to use them on principle, then you're handicapping yourself for no reason. Midrange still wants to be using all of its mana every turn, and having the wrong color or EtB tapped lands keeps you from doing that. Sure, you've beaten some tournament-winning decks, but how many have you lost to when extra mana might have made the difference?

The Boros Guildgates are still strictly worse for you than Mountains in any case.

But you can't play Serra Avenger on turn 2...
And Aurelia is a game-ender; she's expensive because she should be the last card you play.

Like gremere102 suggested, an aggro deck with nothing to do turn 1 is always going to be at a disadvantage. I'd up the Wasteland Viper count to 4 and then add about 6-8 others - Legion Loyalist, Rakdos Cackler, and Experiment One would be my top choices.

Also, I'm not really sure what the Boros Guildgates are for, since your only white cost that I can see is Boros Reckoner which would be played just as easily with 2 more Mountains instead. Maybe replace the Selesnya Guildgates too, lands that enter tapped are too slow for a heavy aggro deck. A set of Stomping Ground would be REALLY helpful if you can afford them, since you have so many dual-color cards.

I've put together a R/G aggro deck with a few bloodrush options if you want to take a look at it for ideas: http://www.mtgvault.com/monty/decks/standard-gruul-aggro/

This seems like it's lacking coherence and speed. You say it's a ramp deck, but you can't actually play any of your ramp cards until turn 3 or later, so by the time you get going you'll probably have already lost. Aggro will just kill you before you can respond, combo will get their combo before you can do enough damage, and control will have answers for all your creatures before you play them. You have literally nothing to play turn 1 besides land, and your only decent turn 2 option is Dawntreader Elk (which still doesn't do anything useful for another two turns, one to get the mana to pay for its ability and another for the land to untap) - Squadron Hawk has no synergy with the rest of your deck, and Signal the Clans isn't that useful if you can't actually play any of your good creatures. You could really use a bunch of mana elves, or at least SOME sort of useful 1 and 2 drops. Also, you have too many lands (drop it to 24 or maybe even lower if you add enough good ramp), and way too many single cards, many of which don't seem like they contribute much to the deck.

I think your problem is a misunderstanding of what "mid-range" means. You should be aiming to play 4-6 mana creatures on turn 3-4 - more expensive creatures than that generally aren't worth casting unless you can cheat them into play, and longer setup than that means you should probably be looking for a more control-oriented strategy.

Can't see why it wouldn't, but since I took all the Blue out of this deck anyway it doesn't matter much.