We have great news for HTC U11 users. TWRP custom recovery is available for download which means now you will be able to flash custom ROMs on it. If you do not have custom recovery, there is no way to install a third party ROM or even install system level hacks. You will also need custom recovery on your HTC U11 if you want to overclock or underclock it as it lets you install custom kernels that lets you do it. The only thing that is not working on HTC U11 is encrypted backups so do use them.
How to download and install TWRP on HTC U11?
First, you will need to download and install ADB drivers and platform tools from the Android SDK on your computer. Get the TWRP for U11 from here and rename IMG file to twrp.img. Then on your phone, go to Settings > About and tap on the build number seven times to enable developer settings. Then go into developer options and turn on USB debugging.
After that, on your computer, fire up command prompt and type in the following commands.
adb reboot download
fastboot flash recovery twrp.img
That is it. If you did everything correctly, TWRP custom recovery should now be installed on your HTC U11 android phone.