Considering people at the place where you go to FNM play a lot of black I would kick urborg out, it might be helping them a lot. Also first change I would make is buy the scry land (e.g. Temple of Deceit Temple of Mystery) if it's within your budget. Nykthos, Shrine to Nyx might be a good addition too.

This deck seems to be lacking any removal, I would suggest running at least 3 Hero's Downfall along with those Murderous Cut. Maybe some Silence the Believers

Also think about using Whip of Erebos, it's an amazing card and every sultai deck i've ever seen is running atleast 3. gets your creatrues back and your life back.

I also think that you could kick Kin-Tree Invocation into mainboard, since you're running quite a bit of big creatures. Since we're talking about big creatures, with your mana ramp you might want to consider playing Sagu Mauler in this deck. 6/6 trample hexproof. Very hard to get rid off, i found myself losing to sagu maulers a few times with my jeskai aggro.

Definitely kick Disdainful Stroke into sideboard and Cancel out for Dissolve.

Also, kick at least 1 Treasure Cruise out for another Dig Through Time.

This is all the suggestions i can think of for now... Hope I helped! :)

Thanks a lot Sugar! :D I'll see what I can do!