Thanks again guys. Managed to remove it tonight - wore gloves and twisted heaps, eventually it gave way.
EV1, I think you're correct. Looking at the thread, it was either loctite or the original factory glue holding it on.
Hopefully my fiancé likes the Nismo Titanium one I got her, we'll find out tomorrow morning.
If not, at least it won't be as much of a mission to remove it this time!
Cheers.