Lots of pressure in fuel tank??

I have done a lot of mods in the past couple of weeks on my new SD. Two of which were a new fuel cap and I also removed the evap canister from the tail section. I noticed today when unscrewing the new fuel cap that there was a lot of air rushing out of the tank. So I took the cap off and tried to blow into the two hoses that used to run to the evap canister (which I just ran to the bottom of the bike) and I wasnt able to blow into either of them.

So my question is: Is one of those tubes supposed to be a breather of some sort for the tank? I'm thinking thats why there is a lot of pressure in the tank when I pull the cap off. I'm just not sure as I'm still on the tank of gas that came in the bike when I bought it. Could I have maybe kinked one of those hoses or something?

Any help would be greatly appreciated.