REQ xthreads updating to 1.8 guide

[Hamster24]

Hi zinga
can you please tell me how to update xthreads to 1.8.
i am currently on 1.6 mybb.
so should i first upload files of new xthread before updating mybb
or should i update mybb first to 1.8 and then upload the xthread files

in short whats the best way to update to mybb 1.8+xthreads from 1.6+xthreads
so that i don't lose any xthreads data i have more than 10,000 threads with xthreads fields filled in other words every thread has xthread in it.

Please help
Thank you