The Sony Xperia Z2 is a great device out of the box, but let's not kid around, a certain number of people are going to want to root and flash it if for no reason other than spite. The task requires a good custom ROM to turn to in place of whatever unbearable software the phone shipped with, and fortunately the latest version of CyanogenMod, complete with Android 4.4, is now one such option available to Xperia Z2 owners who just can't bear to let things be. It's offered as a nightly under the name "sirius," a codename for the Z2 that frankly gives the word "Xperia" a run for its money.
Hey, I get it. I've been there. I'm not going to try to talk you out of flashing that ROM. Heck, I'll enable you. Here's a link below. Flash your favorite custom recovery, and have yourself a blast. Just know that this is not stable software, and anything could happen. Don't come to us when smoke starts pumping out of the device or, more likely, the GPS no longer gets a lock.