I would absolutely mainboard a playset of Lightning Bolt . Terminate is also probably better than Dreadbore , as walkers aren't all that common in Modern. Both of those options are pretty budget friendly. I would try to pick up some Thoughtseize or at least Inquisition of Kozilek , which is significantly cheaper. Rix Maadi, Dungeon Palace is a great utility land for this type of deck. If you want some other ideas, feel free to check out my build. Its not budget friendly, but its a pretty competitive version that features some of the cards I suggested.

kmcree thanks for the feedback, I've updated things a bit to incorporate a bit more removal. I'm going to hold off on buying Thoughtseize until I'm sure I like playing this deck, but I'll think about getting a playset of Inquisition of Kozilek .

Have you considered Surgical Extraction ? It literally t1 rapes combo decks, since you can cheat it out for 2 life. Best discard deck sideboard card IMO, Extirpate is amazing, but I think extraction could be a touch better because of it's speed

teamawesome1, I have considered it, but I like the "split second" mechanic on Extirpate because it means it won't be countered. Also, because I have not invested in cards like Thoughtseize , I don't usually have a strong t1 discard to piar with Surgical Extraction . As I play this deck more I may decide to make that investment. Thanks for the comment and +1

Took out 2xMutilate for 2x Anger of the Gods and put two more in the sideboard. This deck's biggest struggle is against aggro, and Anger clears the board sooner than mutilate, and more consistently. With the check lands and mountains, I generally only have three swamps out by T4 anyway, and I like the exile clause. The only drawback is it doesn't work against indestructible, while mutilate did (to an extent). That is what the sacrifice cards like Geth's Verdict and Smallpox are for.